I posted a long post in a different thread about this yesterday, so you can check it out.
For us it was mostly silent reflux. He spits up about the same amount now, but he's not in constant pain any more. Also, I think soy protein was actually worse than the milk, so if you do try an elimination, be prepared to cut that out too. For me it's just the soy protein. Soy oil and lecithin are still ok.
My son wasn't a screamer, but he was clearly uncomfortable. Lots of squirminess, arching of the back, grunting, fussing, getting red in the face. He made these noises that sounded like a chipmunk or goat pretty much all the time. He was constantly bringing his legs in to his stomach, and it got pretty distended from gassiness. He was constantly restless and uncomfortable in any position, and I'd have to hold him against my chest and pat his back for a very long time after each feeding. Sleeping was the biggest issue, because he pretty much had to sleep on his tummy at an elevation on my chest. That's how we slept for the first 6 weeks or so. Any attempt to lay him down would result in him waking within 15 minutes with the grunting and squirming. Also his poops were very green and were starting to become mucousy.
I was drinking a LOT of milk and eating a lot of cheese, but I noticed it all got better about 5 or so days after I cut it out. Then it took a few days setback to realize soy was also a problem. After that, his stools returned to an orange color, and he could peacefully be set down to lie on his back.
If I ever eat soy or dairy in any appreciable amounts, the symptoms all come back, even now (he's almost 4 months now), so I'm pretty convinced that's what's going on, even though the medical community doesn't really have a mechanism to explain why babies have these sensitivities to their mothers' milk.