First I would note that vaginal bleeding in cats on heat is actually very rare and when it is present its very slight. So, that is not a worry we'd have with Sara, especially with blood on her stool and not mixed with urine. Instead, given what we have here, this is more suggestive of colonic inflammation/irritation. which can be due to parasitic infection (ie whipworms, giardia, coccidia), inflammation or infection of the colon (colitis). It can also be seen with anal gland disease but often they are very painful. And while rectal polyps/tumors also can cause bleeding she is a bit young for that as well.
With this all in mind, in regards ***** ***** approach here, the first step would be to consider worming her at this stage. This would just allow us to rule out whipworms as the root of her signs. Ideally, we'd want to use Panacur (preferable as it will also help with some protozoa), Drontal or Milbemax. These are available over the counter at the vets, pet stores, and some pharmacies. Do make sure you have an idea of her weight before purchasing, so you make sure to get the right dose for her size.
From there, we'd next want to address and rule out inflammatory colitis. To do so, we can often settle these with a light/easily digestible diet. (Though bacterial induced colitis will often require antibiotic treatment). Examples of bland diets would be boiled chicken, boiled white fish, scrambled eggs (made with water and not milk), or meat baby food (avoid those with garlic powder in the ingredients) There are also veterinary prescription diets that can be used in cases like this (ie Hill’s I/D or Royal Canin Sensitivity Control. The easily digestible diet will be better tolerated and absorbed by the compromised gut. We usually will try them on the diet for a week until signs settle, and then slowly weaned back to their normal diet over a week.
If you try the above but do not see her signs start to settle over the weekend (since this has been going on for a wee while already), then we'd want to follow up with her vet at that stage to rule out bacterial causes for her colitis signs. At that point, you may also consider bringing a fecal sample with you for evaluation. The vet will be able to examine your kitty, assess her hydration, and if bacterial colitis is confirmed, the fecal sample can be sent to the lab for evaluation to identify the agent responsible and what treatment will be effective to clear it. As costs are a concern, they could alternatively cover her with broad spectrum antibiotics to treat against the most common bacterial agents of colitis.
So, we do have a few considerations for Sara's signs. Therefore, it would be ideal to rule out the parasitic differential by treating for with a wormer that will address whipworms and trial her with an easily digestible diet for inflammatory colitis. But if that doesn't settle then we do want to have her seen by her vet to make sure there is nothing more sinister afoot for her.
Finally, as costs are a concern, if her signs linger and you have a VCA or Banfield veterinary hospital near you, then you might consider taking advantage of their free first consult offers. You can find vouchers for this via VCA: (http://www.vcahospitals.com/main/offer) & Banfield : (http://www.banfield.com/landing-pages/coupon). Otherwise, you could consider checking out the Humane Society's database (http://www.humanesociety.org/animals/resources/tips/trouble_affording_pet.html) as they often are able to help.
I aim to provide the best care for you just as I do for my own clients & their pets. If you have any other questions, please ask – I’m happy to help but please take the time rate me with the **STARS** (or leave a written rating of 1-5; 5 being great) afterwards as otherwise the site does not credit me for helping you. There is no extra fee for this (its included in your question fee). Once you rate, your question will not close & you can still ask follow-up questions. Thank you for helping me to keep helping everyone here. : )**