Why does my 3mth old jerk his head...

My son is 3 months old now and for about a month he's started to move his head alot when he drinks his bottle. he moves so much that sometimes the bottle pops out of his mouth. At first i thought it might be that he has an ear ache but now im not so sure. Does anyone else have this problem or can help me out, im def going to ask his dr but i thought i could get some info from other mothers as well. please help.

my LO just started doing it today! it drives me crazy!