SI-Glute-Erector Discomfort

I have this tightness in my SI-Glute-Erector area on the left side and I can’t figure out how to correct it. If I sit in a chair and anteriorly tilt my pelvis to stretch it I feel a lot of tightness in that region and some what when I stretch my QL on the TRX but it doesn’t seem to go away. The stretch makes it feel better temporarily but it needs stretched again the following day. Also, for the longest time I have been a stomach sleeper with my head on my right arm, I have since then started sleeping on my back and the pain in the morning has gone away. What I’m looking for, is not necessarily someone else to do all the hard work to give me an easy answer but maybe someone who has has this similar issue and found a way to fix it themselves. Even small suggestions or new avenues to take would be helpful.

Background:

-Can Squat, Deadlift, and Bench respectable amounts without pain.
-6ft tall, 205 lbs, 28 years old, job: manual labor but no heavy lifting.
-Doesn’t hurt to do jumps or to run or any other activity.

So, is it only hurting when you stretch it? If so, don’t stretch it.

Am I missing something here?

I suggest lying down, or standing up more frequently.

Get a foam roller. Roll that shit out.

yes I’ve had this pain. I believe its muscular and you have to foam roll, stretch and maybe do some pelvic tilts and take some meds to get the inflammation down… In time it will get better. and if you can find an exercise to increase blood flow without being in terrible pain do it. a small amount of discomfort is ok. Also you could get a tennis ball and roll back n forth over the sore spot, then heat will also help.