Lower back pain - advice on getting back into lifting/sports

I injured my lower back around 4 months ago after a long weekend of squatting at the gym and playing a lot of volleyball. I went to the doctor and did an xray and all the advice I got was to stretch and exercise my core. I got back in the gym around a month later and flared up my back again after doing lat pulldowns. After that, I was much more intentional about my recovery and since then I’ve been doing core exercises, 90/90s, and back extensions. I’ve also gotten back into playing sports, but I’ve avoided loading my back with back squats or anything similar.

Four months later, I wanted to try belt squats because I heard they don’t load your back and I wanted to get back into training my vertical jump. On my very first set loaded with 60lbs, my lower back flared up immediately after bending over to add more weight. At this point, I simply don’t know how to recover anymore and get back to lifting heavier weights. Does anyone have advice/experience on recovering from this?