My only problem there is extremely tight hamstrings. I'm young, so I just wonder why this would happen.
I don't know for sure that they're tight, but I can barely touch my toes with my legs straight. I work them hard
I know from experience. Hips, hams, glutes, knees and lower back all work together to fuck you up. In my case, it was tight hips and low hip mobility. Low back pain, hip tightness and knee pain were my symptoms. I started working the foam roller on these areas, worked on flexibility in my hips, and loosening of my IT band on the right side. I also started dragging the weighted sled a lot.
My tightness and lack of flexibility led to an imbalance which led to weakness on one side, which caused my back pain and knee pain. Getting back to neutral was key before anything else.
Along the way, I discovered that everything that I "knew" about training and diet (and gear) was completely wrong.
Age has nothing to do with it. Get yourself to neutral. You may need to find a COMPETENT trainer (i.e not some jamoke off the Internet) to watch you workout. You'd be surprised how much a real expert sees that we no longer are capable of seeing.
Good luck.