Why wont my tiger Oscar eat his food?

My Oscar is 3 years old and is in 50 gallon tank. We just moved about 5 months ago but when moved in he would eat fine and now he just comes up to the tank looks at the food and looks away. He has done this before but it lasted only a week and a half. This has been going on for a month now and he has only been eating feeders and blood worms. I thought that it mite be that he is scared so i put some rocks in the tank for him to hide behind but he just pushed them all into the corner. i no that feeders are bad for him but i don't no what to do and i did try other foods.