Our cat (kitten) is almost 5 months old. We got her at 8 weeks and have had no problems. 2 weeks ago we took her to be spayed at a low cost spay/neuter facility our state provides. We followed all directions keeping her quiet, wearing collar etc. After 10 days she seemed to have a big bulge in her belly. She also in the 2 days prior had peed on my son's bed and had several stool 'accidents' in the house. We took her back into the facility and they said she possibly had a urinary infection and I needed to give her an antibiotic (Amoxicillan (sp?) for the next 2 weeks. In the next 5 days she had diarrhea and continued 'accident' throughout the house. Then I took her back into the clinic. They said she was healing fine, the bulge had been tissues healing, and they saw no problem whatsoever. They said they did not know why she was peeing and pooing all over the house and I should go to the veterinarian that their job was done. Now I am in a dilemma, cause if I had had the money for a vet I would have gone to one to start with. This cat was perfectly well behaved with no toileting issues before I took her to be spayed. This morning she poohed right on the floor in front of our couch and it was not diarrhea (so that rules out her not being able to make it to the litter box). We have a 2 story house and keep a litter box on each floor to accommodate her needs. She had no toileting issues until she was spayed. Please help!

It may have very well been a urinary tract infection, unfortunately the only way to know for sure is to have the urine checked by a vet.
Lots of times with a UTI the cat associates the discomfort and pain with the litter box and will develop an aversion to it.
As far as the stool goes, Amoxicillin can cause abdominal discomfort and diarrhea again, another aversion to the litter box.
The place to start is ruling out the possibility of a UTI and going from there.
Is it happens that she does have a UTI be sure to tell them about the diarrhea on the chance that it was caused by the Amoxicillin they could prescribe a different antibiotic.
In the meantime make sure the litter is cleaned often (cats don't like a dirty toilet usually) and perhaps try a different litter in one of the boxes to see if she has a preference.

Thanks for explaining all of that because it helps to understand what could be going on with our cat. We went and bought a different litter and stopped the antibiotic. So far, so good. No accidents yesterday. We put her in a small closed room and put the litter box in there with her and she used it. After that we let her run lose in the house and it appears there are no more accidents this morning. Hope it stays that way :-) thanks again :-)