Greetings, I am Dr. Pat. I have worked with birds for many years. I will do my best to help you. I am sorry no other expert has taken your question. We all come online at different times, I have just logged in and saw that you have not been answered. I hope I can still be of assistance.
All of your theories are possible but unfortunately there are many more to choose from. It is an excellent idea to have a bird-experienced vet examine her and take some lab samples. Even if she has a simple foot injury, it would be best to rule out other etiologies.
Has she had eggs or reproductive behavior?
Here is a list of things I would want to investigate:
metal toxicity (being a cockatoo, they chew many things that are not bird-safe that you may not even realize are dangerous)
calcium deficiency (dietary and/or reproductive)
other viral, bacterial, fungal or parasitic infections
chronic trauma (as in your theory of catching the nails)
head, spine, pelvic,hip or leg injury
nerve damage from injury, toxins, nutritional
If you feel comfortable with it, examine the bird thoroughly, using gentle restraint via washcloth or hand towel: do not restrict the chest or hold around the body. Check the eyes, nostrils, mouth and beak if possible, having a good look in there for mucus, redness, masses or anything else unusual. Palpate the tummy for pain, fluid, lumps or anything else (eggs, if female or unknown). Check all the joints for swelling, pain, and mobility. The feathers should be parted to view the skin, muscles and skeleton below; this can be done using a q-tip with isopropyl alcohol or KY gel. Look for bruising, lacerations, injured feathers.
Your job is to keep the bird warm, safe, quiet, and confined; and to provide adequate hydration and calories.
It is very important that she not waste her strength or risk further injury by clinging with her beak.
Move the bird to a box or carrier with soft towels in the bottom, no perch, and food and water in low bowls that can be reached easily. Put the whole thing on a heating pad on low or medium. Check it frequently, no overheating allowed! Keep the unit partially covered, warm and quiet. White paper towels or white cloth towels will show the true color of the droppings. Small animal/reptile boxes are great for this purpose.
The bird, bowls and unit must be kept very clean.
Here are some helpful links:
Do not try to force food or water. Pedialyte or electrolyte replacer can help but many birds do not like them; when in doubt, plain warm water is best. They can hydrate from oral fluids almost as quickly as IV if the GI is functioning properly. You can offer warm cooked rice, pancakes, cornbread, grapes, melon, greens in addition to normal food.
Pet/feed store medications and home remedies are harmful, ineffective, immuno-suppressive, and make them much worse and may interfere with the veterinarian's diagnosis and treatment. Do not use them. Homeopathy and natureopathic techniques do not work in avians and can actually be very dangerous.
I know it is expensive, but you may not have many home options, because the first thing you need a vet for is to find out what is going on. Treatment is only as good as the diagnosis. If you call around, you may find a vet to work within your means. I really must stress that you need a bird-experienced person, and not just a vet who advertises that they care for birds.
You need to take your bird to see an avian-experienced veterinarian ASAP for complete examination, diagnosis and appropriate treatment. Check
Unfortunately, this list does not rate competency or experience, but is only a starting place; the vets at least take the avian medicine journal and hopefully see a bird or two a year. The best referrals are word-of-mouth, so check with several non-bird vets, the humane society, parrot rescue groups, bird clubs, etc. for their input. As you might guess there may be controversy and varying opinions even with this. Even board-certified avian specialists may not have a lot of practical bird experience. Unfortunately there are few resources available to refer you to really good, clinically-experienced bird vets.
If this were my patient, and money no object, I would start with complete fecal analysis and direct smear, stained with Sedi-stain and unstained for multiple parasites, fungi, spirals; direct smear stained with Sedi-stain and unstained of the oral cavity; bacterial culture and sensitivity of the feces and choana. Depending on the case I might do a fungal culture. Routine blood work is necessary to rule out other issues. There are MANY DNA/RNA tests for bird diseases. Ultrasound is often more informative than radiographs and does not require anesthesia (ask your vet about this option). Generally I start them out on medications as indicated by the tests.
Your bird may need injectable fluids, calcium, antibiotics and many other medications. Act quickly and good luck.
Here are a few suggestions that I give everyone: important!
The following guidelines help with basic issues such as nutrition, obesity, good immune status. Surprising how the following can make a bird healthy, and how infrequently birds are ill if they are on the following regimen. No amount of medicine is going to work if the birds' basic needs are not met.
Birds should be on a high-quality, preferably prescription, pelleted diet: I prefer High-potency Harrison's
In addition, they should be offered dark leafy greens, cooked sweet potatoes, yams, squash, pumpkin; entire (tops and bottoms) fresh carrots and so forth. No seeds (and that means a mix, or millet, or sprays, etc. etc.) and only healthy, low-fat high fiber people food. A dietary change should be closely monitored and supervised by your avian vet.
Birds should get 12-14 hours dark, quiet, uninterrupted sleep at night. Any less and they can suffer from sleep deprivation and associated illnesses. They should be covered or their cage placed in a dark room that is not used after they go to bed.
The cage material should be cleaned everyday, and twice a day if the bird is really messy. Paper towels, newspaper, bath towels are ok. Never use corn cob, sawdust, wood chips, or walnut shell.
Food and water dishes should be cleaned and changed daily. Keep one set cleaned while the other is in use.
Fresh, perishable food should be placed in separate food bowls. Remove fresh food from the cage after a couple of hours to avoid spoilage.
Change cage papers daily, and clean the grate and tray weekly.
Clean food debris or droppings from toys and perches as needed (which can be as often as once a day).
Grit is not necessary for birds, and will cause digestive problems and death. The best sources of minerals (and vitamins) are leafy greens. Never give grit, gravel sandpaper or cement perches. A bird will eat those to excess when it is not feeling well or if there is a nutritional deficiency. They do not need it at all (an old myth from the poultry days, even poultry do not need it). It can cause an impaction and lead to serious or fatal consequences.