Newborn spitting up constantly

My son, 9 days old, spits up constantly. Like, gushing amounts. He only nurses for like 10 minutes at a time so I don't think it is because he is eating too much at a time. My daughter nursed for way longer sessions and never spit up at this age. But it seriously happens a lot, not every time he eats but often. Usually within a couple minutes after eating. I take care not to jostle him around too much after he eats. Sometimes it happens when he is on his back, sometimes when he is upright. I can't make sense of it. Help!