One year old refuses to eat anything

My boy who turned one year old this month was a fairly good eater all this while. He would eat fruits, veggies, dals, chapatti, rice, dosa, idli chicken etc. But recently he came down with an infection resulting in cold and fever. He was on medication and has now improved. The cold still persists which Im thinking will go in a few days too. I thought he wasn't eating well because of the medicines. The dosage got over yesterday, still he refuses to eat. And its not like he is having a lot of milk. He is on breastmilk and is fed only during sleep. I obviously fed him more when he was sick and not eating anything and I had to let him have more fluids since he was on antibiotics. But now he is back to 3 feeds a day including night. Still wont eat. I wont say wont eat but not as well as he would earlier.
Will his appetite returns when the cold is completely gone? Or I am in for some serious trouble?
Also he has been sleeping a lot all this while. I figure its because he is sick. Otherwise when he is up, he is all happy and playing. Does that sound normal?
Please help!