my 4 mo. old kitten has had his 3rd eyelid showing for about 4-5 weeks. He's frequently licking his bottom but I see no worms nor any in his stool. He has had a few loose stools with a little vomit as well. He's also much thinner than his sister. Now my other cats have their 3rd eyelid showing, upset tummies and sneezing. Vet at the animal shelter said nothing is wrong but my gut feeling is otherwise.