When I first adopted my Pumpkin I found out that she had roundworms. I never actually saw any worms, but her stomach was huge for a little kitten. Luckily we got her treated in time so she didn't spread it to my other guys.

Since there are different kinds of worms, the best thing to do would be to bring a fecal sample to the vet (it wouln't hurt to bring a worm too). With the proper meds, your kitty will be fine and free of those nasty worms before you know it!! Best of luck!