Id have them checked out for TF as the other posters said. When I got my Bengal Girl that was the first thing that I noticed was her horrendous gas and non solid stool. It was not like diarrhea but just not solid. She could clear the house out. I ended up having to put the litter in a spare bathroom and leave the fan on most of the time.
I have a great vet but he had no idea about TF. I am fortunate to live in North Carolina where the leading Vet on that does her research. A huge double digit number of pure bred cats suffer from this. There not sure why but its most likely a combo of conditions. The main being that alot of breeders trade queens apparently.
TF is not a worm its a protozoa so deworming does nothing. It causes your cats intestines to get inflamed causing a great deal of gas and stool issues. Your cat can outgrow it and no negative issues will really happen if it goes untreated other then terrible bowel movements. It can also be spread to your other cats from the litter. The only blessing of it is that it does not live outside the host for long at all...a couple hours. Thats why a stool sample must be fresh to get a accurate test done. A day old specimen is worthless.
As your vet to test for it..most likely he/she is clueless on it. I printed out this entire PDF to give to my vet and about a week later he told me after reading it, doing some research and consulting with her colleges that she had learned something new.
A fresh sample is preferred so I brought the cat in. They mailed it off and sure enough she had it. Theres a very routine medication that they use for it but its not something normal so they had to order it from a compounding agency. 2 weeks of using that and my cats going to the bathroom like any other cat. If she does have that I would encourage throughly trashing your litter couple times a week and throughly bleaching the litter pan..pain in the butt but its transferred by your cat walking in the litter then cleaning herself after.
Also your vet most likely does not also test for this...so you can test every day for worms and it will always be negative.
http://www.cvm.ncsu.edu/docs/documents/ ... _final.pdf