8 Month Kitten With Diarrhea

Hello everyone! I made an account specifically to ask these questions but I am probably going to be lurking around forever. =p

I got a kitten over a month ago and he came dewormed etc (from the humane society). He has had diarrhea since getting him. The vet initially just told me to keep an eye on him, that it might be him adjusting to new food. Well, over a month later and he still has it bad; gas, farting, smells, gross. We went back today and he had a fresh fecal sample taken and tested. Negative. So, they sent me on my way with him getting another dewormer (just in case) as well as some antibiotics. 

I plan on switching his food (on Iams now) to Purina... Should I wait till after the antibiotics?

Also, I do have a second cat who is perfectly normal. I want to feed the sick cat only bland rice and chicken for a few days and see if that helps at all. But how do I go about feeding the other one. Both are used to food being out 24/7.

Should I just offer the healthy kitty food and if she doesn't eat it, take it away and try later? Will she get the message that she has to eat when it is offered to her? The unhealthy one should be much easier to get to eat as he will eat anything.

Thanks everyone. =)bb

I would get her checked for the other parasites that aren't routinely checked for.  Coccidia, giardia and tritrichomonas foetus are three that aren't routinely checked for.  Tritrichomonas foetus is one that is often not checked for, vets think of it as something only found in cattle.  A sample has to be sent off for testing.  You could ask for a PCR test to make sure there are no parasites.  http://vetmed.tamu.edu/gilab/service/assays/tritrichomonas

I  agree on the PCR test as its more reliable, and sometimes vets want to start treating for parasites on suspicion alone, especially given its duration.  But a PCR test should come back in a few days.  Giardia and Coccidia are likely culprits and either could be considered dangerous if not treated.

What antibiotic did they put your kitten on?  It is quite common for kittens coming from shelters to have giardia and/or coccidia which are the most common causes of diarrhea in kittens.  If your vet didn't I would ask them to send in a Fecal Panel to check for the Tritrichamonas parasite, which is an often overlooked but somewhat common parasite.