Just throwing this out there. A few weeks ago I bought a rode bike and have been struggling with fit issues a bit. Most are really saddle related. Too much pressure in the wrong spots leading to unnerving, post ride numbness. Also, I was having some low back pain towards the end of the rides that ended as I got off the bike.
While playing with fit things, my most knowledgeable buddy suggested it might be a clothing problem. I have been losing weight quite a bit and have still been wearing the same 3x Aerotech bib shorts. I noticed they were getting a little loose, but I thought all fine. My friend suggested trying a size down of the Specialized RBX bib shorts. I got them, they were a little tight on the first day, little more form fitting the next. But my "fit" issues disappeared with only that change. No more numbness, no more back pain doing the same rides.
Something to consider if in similar boat.