Help! my bunny may be sick?

well hes been acting very weird like yesterday he just sat sitting like this a href="http://us.123rf.com/400wm/400/400/elenat…" rel="nofollow"http://us.123rf.com/400wm/400/400/elenat…/a all day and when i tried to feed him and he ALWAYS takes my food he didn't want it and he HATES being in his cage so i was surprised when i found him just sitting the same way in his cage. and every morning when i call him for breakfast he runs upstairs so i can feed him but toady i found him sitting there in his cage like yesterday and i went to feed him and he didn't eat im very scared!! please give me some advice please! hes a boy hes like 1 year old and hes the only bunny i have so please help me!! oh and btw he lives in our basement and its cold down there so do you think he has like a cold? but we took off the air conditioning downstairs for hershey (that's his name) so its not cold anymore