Not sure if he is eating enough

I have a neutered 1 year old male. Before he was fixed he was kind of chubby and muscular. Now he looks like he is not eating. I got him fixed in January. From then on he does not sleep in his bed out in the carport. His sister had kittens about three weeks ago and is now in the house. They would sleep in the same bed together and play all the time. Now he is sleeping out in the woods in the back of our house. I have to go back there and get him to come and eat or just to see him. He will at night come up to the house but by morning he is gone again. Could it be that he just misses his sister right now? When I do see him eating he is very nervous and jumpy. If my sons or husband goes outside at anytime then he runs back into the woods. I do sometimes give him some cooked chicken but he does not always eat it. I have also noticed that he is not very aggressive anymore. His new friend is now our poodle.

Does he look like he has lost weight. Maybe he is eating in the woods. I think it is safer to bring him in and let him be inside. Maybe he will settle down.

TIme to get to the vet...