I have had one kitten for 2 months and the other for 2 weeks. The one I have had for longer has always had on again off again diarrhea. I treated her with antibiotics a while back just in case it was a parasite. Right now diarrhea is on again with stinky gas. My other kitten that I have had for 2 weeks also has on again off again diarrhea. Right now it is the worst I have seen it and he also started vomiting this evening. He still wants to eat and drink after vomiting and has energy. I currently give them both Purina Pro Plan for kittens. The older kitten has always been on Purina but the new kitten was on hills science for kittens at the humane society and I transitioned him to the new food. Should I try a different food and if so, what kind for this stomach issues? Should I try a probiotic too? Brands would be helpful....that could be purchased at petco or petsmart. One kittens is 3 months and one is 5 months.