Baby formula?

Ta

My son will be 3 months next Saturday and he's been spitting up since birth, he spits up a lot, it's like he's throwing up all the milk and I've tried giving him 2 ounces then burp him and then another 2 ounces like someone suggested but he still does it, I've been prescribed 2 different kinds of similac milk from my doctor but nothing and I've went out and tried every single last kind of similac but the alimentum

Which is the one above, and a friend suggested soy milk but before I buy I would like suggestions on what others think might be the problem? Or what milk to try ?

He just started drinking 3-4 ounces