my two seven month old kittens have been having severe diarrhea for weeks now. i took them to the vet for a check up and brought in a sample so they could test for worms but it came back negative so the vet put them on a special diet and anti diarrhea medicine but as soon as the medicine ran out the diarrhea came back. i was getting very concerned so i made another vet appointment and brought in another sample and asked them to test for coccidia but that test came back negative too... the vet gave me more of the medicine but they had the last of that almost two weeks ago and now the diarrhea is back full force... i don't understand what's wrong... i tried changing their diet and i make sure that they don't have any dairy product but nothing seems to rid them of their horrible diarrhea. They seem healthy and playful otherwise but the constant diarrhea is really starting to worry me and i don't want to keep wasting time and money at the vet if they can't even figure out what the problem is. please help me if you have any ideas of what the problem could be. Thank you for all for your help