Well, I have two problems.
1) Pain around the tail bone. The deeper I go, the more it bothers me. Nothing I can't live with, but something I am a bit concerned about and want to play it cautious. This seems to be coupled with some knots in the very lower back. I expect this issue to clear up pretty easily with massage and rest.
2) A sore lower back. Not joints, not bulging discs, not sharp pain.....just a dull ache. Imagine if you really worked the hell out of your lateral delts and they just burn. Like that, except that imagine you have to use you lateral delts to hold an object out to your side all day long. That seems to be the big problem. My back will get so sore that it just aches all day any time I have to support my torso with my core (like right now as I sit up to type).
10 years ago I built up to a 375 lb squat (which was a huge deal for this skinny distance runner), which was great, except that I'd go out and play basketball and could only get through a single game. I'd then have to go and lay down on the ground for a good 10 to 20 minutes because my back hurt so bad.
Yes, this is the quandary I live with......my back is too weak to work out, but if I don't work it out, it will never get strong.
.........not sure what to do about it. = ^ /