10 day old projectile vomited

Just now, I've never seen a baby vomit like that. I had him propped up on my knees, and he was calm, and then suddenly he just spewed out all over the place so much vomit and it scared me to death. I put him on my chest so he could breath and get the rest out. This was right after he ate about 2 to 3 ounces of my milk that I just pumped. He has been getting a sour face to my milk and reluctant to eat it. I'm not sure what is going on. Is he allergic to it, am I eating the wrong things, like what could it be? I give him formula here and there when I can't keep up with pumping or feeding, but he hasn't had formula for hours, this was right after a bottle of my milk. Idk why he makes that sour face either, but he doesn't like it or something... and if I give him formula, he is fine, no sour face... someone help? By the way, he is okay now