bottle feeding help!

Hi ladies! So i am a FTM and my son is 2 months as of yesterday. I am having some problems with bottle feeding him. He takes the milk fine and drinks fine. The problem is that sometime while sucking he will push out the milk from the sided of his mouth. Why is this happening? He does it a lot. I have tried changing the nipples i use and even changed bottles. What can i do so this stops?? Also because he spitting out the milk his skin is breaking out, it is down to his neck, what can i put on him for that? For now im using vaseline