My 6 month old kitten, Henry has had an upset stomach (the runs) and been off his food since Tuesday night. I'd given him some cat treats at the weekend and on Monday that he hadn't had before and on Tuesday I thought that was maybe what had caused his upset stomach. When I got up on Wed morning, he seemed fine, ate his breakfast no problem and was being his usual self. I didn't give him any treats, just incase it was them that had caused it. When I got in from work on Wed, I discovered that he still had the runs and he didn't want to eat his dinner. This morning, he only ate half his breakfast and has just nibbled at his dinner tonight and he still has the runs (although it doesn't seem to be quite as bad today). I haven't given him any more treats, I've just been giving him his normal food. Apart from the treats, nothing else in his diet has changed, he doesn't go out so couldn't have picked something up and eaten it. He's his usual self in every other way, he's still playing and jumping around as usual and he's not sleeping any more than normal. Should I take him to the vet tomorrow or do you think it will pass?