Diarrhea in Young Adult Cat (a bit long)

Hi Everyone,
I am hoping you can help me out. About two weeks ago I found stray on the street and brought it to the MSPCA. I felt bad about it being there and went back and adopted it (he is about two years old). About a day after he came home with me he started getting diarrhea. I took him to the vet and they said they thought it was probably because he is stressed from all that has happened (street to MSPCA to new home with resident cat) and also new food. They had me start him on 1 ML of Flaggyl twice a day. Well the Flaggyl made him nauseous and he wouldn't eat. So we cut the dose in half. The I realized that he had been eating a LOT of food almost the entire time I had him. I'm talking probably at least two cups of dry a day and a quarter can of wet food. He was also eating rapidly. I assume he is doing this because he was without for so long. So I started giving he smaller feedings of about half a cup of food a day. I did this about 4 days ago. He has now had diarrhea for about 11 days. We are know trying to switch him slowly over to W/D (high fiber) to see if it will help (started this about 2 days ago). He goes about 3 times a day and it is partially formed. Otherwise he plays and is in a good mood and the vet said he is not dehydrated at all. I am worried though. I have all of these horrible images of him having cancer or some other horrible disease. He is young but it is still a possibility. Has anyone ever had a new cat have diarrhea from stress and/or food? Any help would be appreciated. I am sick with worry.

it used to happen all of the time with one of my cats till I switched her off of a commercial diet to a natural diet of meat.

I would take him back to the vet or to a different vet as soon as you can.

Second the vet ... I also have found a meat based diet wheater raw or cooked can help this

I second a second opinion...have them rule out giardia and coccidiosis, and/or consider treating as if there is giardia. I'd stick to the food you currently have until you are sure there are no parasite's involved...if you are changing foods often, it will be hard to tell what the cat is reacting to.

Btw, what are you feeding currently? And has the cat had blood work done - thyroid okay, no sign of diabetes?

We haven't done blood work yet. We have done a fecal sample. There were no parasites but we dewormed him again anyway. After a few days on the medicine his stool has started to form somehwhat so she decided we should wait a couple more days and see if he continues to improve before we test his stool for other problems. She said even if one of these other things popped up in the stool the Flaggyl would treat it anyway because it is an antibiotic. She wanted me also to give him a few days on the W/D to see if he improves. If not then we would do blood work.

Personally I wouldn't wait. Eleven days is a long time to have diarrhea. I really would get another opinion if I was you.

Good luck! Please keep us posted.