Deadlifts and broken backs

I love deadlifts, the setup, technique, and for me when either of those are off I pat for it. What I hate is "paying for it" but not seeing or knowing why. I was able to accomplish my prescribed sets and reps with the last one resulting in something going on in my back. I let the weight down and I locked up, needed help to the floor and got in the 90/90 position which gave relief. The rest of the day was slow moving and a belt needed to be worn just to cope with the pain. I was able to have an emergency visit with our chiropractor later that evening and he informed me the good news that it was not a disk but muscular (best case scenario). Fast forward 24 hours and I am feeling a lot better and our massage therapist concluded "It is really more of a gnarly QL with a little pissed off psoas and erectors. All of this is good news except for the fact that I was unable to see what happened during the lift to diagnose why I got hurt, hopefully this was just a mishap and will be ironed out after this event.