Chronic lower BP, L2-5 bulging, think I just pin pointed the issue - any tips?

I've had the diagnosis of those 4 bulging discs, degenerative disc disease and narrowing of the spine for about 10 years now. Most days are fine, though I get a couple days a year where I can't be off the couch without tremendous pain and I have some muscle relaxers which helps a lot for those times. I've previously done steroid and facet injections, physical therapy, yoga, continued to work out... Nothing has really helped. The neurosurgeon that I worked with when I got my diagnosis was trying to prevent surgery as I was in my mid 20s back then, and I'm still a bit concerned with that.in the future. In any case, I've never really understood where and when the back pain comes from until yesterday in particular.

I was packing up some stuff for a move and had to carry some things up the stairs. It wasn't anything heavy or particularly large. Maybe a 1'x2" box weight 30-40lbs. As soon as I took a couple of steps up the stairs, I felt my back go into an anterior pelvic tilt and basically crush ome of my nerves. Back has been sore since. I had to move a few other small objects of maybe 10lbs max and felt my lower back roll forward even then and it was definitely a mindful challenge to really embrace my core while doing what seemed like something I shouldn't have to do it for.

The kicker is that I've been tested for anterior/posterior tilt before and have been found that I do not have it - at least not under "normal" activities like sitting/standing/walking/running, but have never done tests while carrying any kind of weight. Is there anything that can be done to fix it while the spine is under load?

I already work out 2-3 days a week and hit my core and (lower) back in particular with exercises my previous PT recommended, so i don't think it's a strength issue. I suspect some of it has to do with just overall body mechanics of being 6'5", but as I won't be without non-emergency insurance for a couple of months while I move, get settled and find a new doc about it, I'm just trying to see if anyone may have some advice in the meantime besides "just embrace your core 24/7 then."