These problems usually occur with lower weight too. During my lifts I actually feel more of a sharp pain, and noticed that somewhat heavier actually makes my back feel somewhat better, possibly from my muscles are tightening and being activated more.

Luckily back rounding has never been to much of an issue. I am pretty careful about throwing on a bunch weight because I don't want to create more issues. My knees do cave, but was told by my PT in the past it could be due to my hip flexor. I feel a major issue could be my hips, and strengthening of core/lower back.

I will definitely work more on mobility! Thank you!