So I did squats yesterday and overall I'm still not sure where I stand.
I did the thumbs around grip and while I think it helped prevent the shoulder pain, I did feel alot of pressure on my wrists and some on my elbow still. It definitely still hurt just in different ways. Instead of brachialis/shoulder, I feel a little tennis elbow and wrist pain. Maybe it's because my arm is still sensitive. Maybe my wrists will get used to it (it didn't hurt the wrists, but definitely felt alot of pressure, even with wraps). Overall it still didn't feel great, but maybe it's because I need my arm to cool off a little.
Chris, Its funny you should mention my thoracic extension. This was one of the other things I was hellbent on working on yesterday. Then I realized/remembered why I hunch over. At the lighter weights, the thoracic extension feels GREAT and I DO feel more solid. But as the weight gets heavier, there is just no way I can do the thoracic extension because the bar just literally slides down my back then. I tried this again yesterday. Thats why I hunch over at the top. To keep it on the shelf. This lack of really solid shelf is also probably why my arm gets so badly inflamed. Kind of thinking about it, my arm REALLY started getting inflamed around the same time Tom mentioned the extension and I tried standing up straighter. So if it's not just a coincidence, that could be the straw that broke the camels back.
My arms are indeed carrying alot of the weight, one way or another. 225LB feels fine, the bar holds steady, I can start with good thoracic extension and nothing really hurts. 285lb and everything feels wrong. As I mentioned, I can start with thoracic extension, but then my arms are begging for mercy because they are literally holding the weight from moving. It's probably so intense from the combination of being at my flexibility limit and then applying a ton of force on it.
I tried moving the bar around to see if there is a better shelf, but outside of the "on top of the traps" high bar position, there is none. The bar is very comfortable in the spot below my scapula, but obviously it does start sliding at heavier weights.
So I think if I figure this out, I will be able to figure out my arm pain.
At this point, I don't know what to do.