This problem is often related to arm pull. If you start bending the elbows and pulling with the arms too early, it puts the bar in the position to nail that pelvic bone. It might be such a tiny difference that it's impossible to see visually. I've had that problem in the past. As you said, it's incredibly painful. Try thinking about longer arms through the middle of the pull and that might help. Good luck.
I was at a national meet a few years ago and Lancy Frye had been having this problem. He was working out in the warmup room the day before he competed and having trouble snatching 90 because it was so painful. We talked about possible arm pull issues being the reason, and the next day he snatched really well with no pain in the meet. I don't know if that was the exact reason for his problem, but it's food for thought.