I have this semi wild cat that was abandoned by someone when it was a kitten and has decided to 'live' with me. I got him neutered etc and give him flea and parasite protection. (I am highly allergic to cats so he has to live outside and has access to our garden shed through a cat flap)He was always a bit of a wanderer and would disappear for 2 or 3 days at a time and always come back very hungry. This last time he went for about a week and has just returned he seems very happy to be home but he isn't eating, even though he is very skinny. I gave him some food and he ate a tiny bit and drank a tiny bit of milk. What do you think maybe the problem?