Lower Back Muscle Imbalance

Hello… have had a number of chronic pain issues the past ~6 years… TOS/Radial Nerve entrapment @ scalenes/etc,etc another story for another day…

-typed more than i thought i would, if you dont want to read it all (dont blame you), skip to the bottom under the ----------

Anyway, I first noticed this in HS when I was 16 or 17 (I am now 23)… my lower left back “swells out” further than my lower right back. Initially when I noticed this, I had strained or pulled something or whatever which caused the swelling to increase even more. This has happened several times over the years, but always goes away in a week or so. The normal imbalance though is still prevalent… I initially thought it was some sort of inflammation or trigger point issue–some sort of injury.

However several therapists, chiros, etc have told me it is just muscle. How I built up the one side, I am not sure (it used to tighten up on pushups perhaps due to faulty form/failure to tighten core/torso when i was younger-this may have allowed one side to slouch, leading to an imbalance over time)… regardless it is over and done with…

question is, how on earth do I build up the other side? Is there anyway to isolate it perhaps isometrically? I know the answer is not complete rest of the entire lower back until it balances because i tried this (indirectly due to other injury) over a 2 year period of zero exercise… i know for a fact this imbalance is causing issues… for one, my left hip, glute/piriformis area gives me a ton of issues…

also i have had pins and needles above that “swelling” in the lower traps/rhomboid area (also causes issues into the side ribs) since i was 19… this pain/pins and needles increases when leaning forward(brushing teeth), sitting with no back support (core strengthening has helped this), and holding anything in my left hand out in front of me (ie carrying a plate to the sink)… also working with my arms/hands out in front of me (doing the dissues/folding wash) causes very very very bad back pain–not sure if this is related

another major issue I have noticed is if I am sitting on a couch, or sitting up in bed, and my lower traps/rhomboid area isn;t supported well, the other side of my lower back (the not as built up side) goes into spasm, and i swear i get crazy tightness down into my groin, up into my lat/trap/neck/scalenes, into the shoulder, with nerve pain into my hand (all only on that one side)… it is like a domino effect… it was only about a year ago i found out the source was my mid back muscles–i lay on a baseball just on the tender points in my mid back and all of that tightness is gone in minutes… i wonder if this issue keeps arising due to that weaker side attempting to overcompensate for the stronger corresponding side by tightening?

-lower left back is built much more than right (very visible to naked eye)
-causing a number of issues especially with nerves/referred pain/spasms
-is it possible for me to build up that right side? (without building up the left ofcourse so they are back in balance)

one more thing worth mentioning, never deadlifted or lifted heavily/regularly when this problem arose (i did work out though)… i do now deadlift, and am always told my form is great, but it is just building up both sides equally meaning the left is still more swollen

Thank you so much sorry for storybook