Food follies

Okay, I know that I am not the only one who has had to deal with this problem, but I am getting frustrated... My son is 15 months now, and has refused to eat normally for over two months now. All my 'mom' friends say he should be eating whatever we eat by now, but he won't, and I am at a loss. He is refusing third stage baby food, won't even give most of what I put on his tray a chance, and if I try to put something in his mouth so he can at least taste it, he screams at me like I am offering him boiling oil. He will eat some things, like graham crackers and cheerios, and peanut butter sandwiches, (only if I cut them up and feed them to him- offer him a 1/2 sandwich of his own and it ends up on the floor...) but I can't seem to move beyond this stage. I have been told to just put food on his tray, and if he doesn't eat it, he doesn't eat. It doesn't work, he just has a meltdown and falls asleep. Any one able to share some worldly wisdom?