I've created this account pretty much only so I could find a solution here, because this has been going on for a while now - 8 months.
On my first ever deadlift attempt ages ago instead of giving myself time to learn proper form I rushed it, lifted with a bent back and got a muscle strain. It went away in about 5 days, but then a few weeks after that I started having much milder but more persistant pain in my lower back. I ignored it for a while but squatting seemed to worsen it so I went to check it out.
My doctor was useless, but a masseuse told me I had very tight spinal erectors. The massages themselves didn't help too much, but two things in particular did: the cat stretch and the tennis ball massage. This removed enough of the tightness that for the past 3-4 months I haven't had the slightest bit of pain. But my back is still tight, squatting with proper form makes my back feel like it's tightening up (and it does) and I haven't deadlifted since.
I have no spasms and it's equally tight on both sides. My hamstrings aren't tight, I don't believe my glutes or hams are weak, I have no pain whatsoever anymore so it can't be a spinal issue like a herniated disk, I've had an ultrasound done and I have no muscle tears, but this still hasn't gone away. The only thing I'm not sure of is whether or not I have anterior pelvic tilt, but if I do it's very mild. This is hardly debilitating but I'm very ambitious about bodybuilding and having to hold myself back has meant I've spent these past 8 months stagnating at only 155lbs, so I still have a ways to go.
My previous methods have stopped having an effect, what do I do, and what has even been causing this?