Lower back straining issue

[One Badass Mofo]

Hi guys, recently I have began feeling straining sensations from my left lower back region (indicated in the pic). This straining can happening anytime such as post-workout and even after I sit on a chair for too long.

I suspect it is because of an muscle-inbalance issule. my muscles on the opposite side (right) of my back is weaker, and this in turn causes my left side to use more force for everyday activities and creates a lot of stress. (I made this observation after noticing the back muscles around the spine on the left side of my back is visibly bigger than the right side.

the circled red region is where I can feel straining.


Does anyone have any experience or knowledge about this matter? I am thinking of strengthing the right side of my back through exercises but any other advice would be welcomed.