Greetings, I am Dr. Pat. I have worked with birds for many years. I will do my best to help you.
Mites are actually quite rare in pet birds. If your vets are not experienced with birds, and if they did not do much testing, I would recommend finding another vet ASAP. What did they do for her? If this was mite infestation, for real, premises are the prime target for treatment. They only feed on the birds at night.
This could be a very serious problem. There may be nerve pain or nerve damage from the spine, pelvis or hip area. Any injuries on the leg can cause this as well. Did she have a fall or other trauma?
Has she gotten into anything?
Have you looked very closely for hairs, threads, fibers wrapped around her leg?
Have yopu double-checked the under side of the wings--if the large feathers are injured at the base, blood will appear on the leg and it will look like the leg is injured when indeed it is the wing feathers. They can hurt their wings if woken up in the night.
Any rodents or insect pestsd that might be bothering her at night? what about other pets, children, people in the house? Birds need dark, quiet, uninterrupted sleep at nigh for no less than 12 hours. They can become disturbed, restless, irritable and hurt themselves with sleep depravation.
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.
Does she have routine shower or bathing? 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 these links for more local people:
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.
Feather and self-injury issues can be caused by a multitude of things, including bacterial skin infection, viruses, fungal infections, allergies, metal poisoning, hormonal flux, psychological or combination of these factors. The difficulty is diagnosing the problems and assigning an intelligent treatment plan. Your vet will want to run a number of tests so that appropriate medications can be prescribed.
What is her diet? both for cause and healing it is important that she be on a good diet. Ringnecks love food and it is easy to have them eat right.
Get back with me and I will try to be more specific.