My son is having problems eating. Can anyone help me?

My son frequently does the same thing. He is hungry, but pushes the bottle away, but then is angry because he's not eating. If he does eat then he spits up (only projectile vomited once because of this, usually just spits up). What I have found to work is when he starts to push the bottle away give him a good burp. Even if he is screaming like crazy I won't give him the bottle until he burps. As soon as he burps he instantly calms down and then I give him back his bottle. I think he does this because in that little body there is only so much room and if a lot of the room is taken up by gas then it's uncomfortable to eat, but he is still hungry and is feeling the hunger as well. Hope this helps!