Ok, I feel for you. Can't diagnose but have a similar story.

I was living in a small resort town in Appalachia, few doctors.
I shoveled my 60 degree driveway for several day. I used the same position for the shoveling and was so pleased to have found one that worked with ease.I was about 65. I have PTSD, new, corrupt nerveous system but had never experienced nerve pain.

I was fine for a couple of days. One the third day, I awoke and was having trouble walking. Difficulty reaching to the floor for my dog's bowl. I had shooting pain from my waist down. Each shot of electricity caused fierce pain, nothing like I had ever experienced before. Therefore, I knew it was nerve pain.

No pain relieves helped. I went to chicago to visit my daughter, still in terrible shape, and broke out in the hives. So, I put myself on Deltsone, 70mg. the first days. All the nerve pain vanished. (Becasue of intervention by a non-profession on a half board the pain had gone from my waist to my neck. One day I reached up in a cabinet, and felt a shooting pain of about a second length, go from my upreached hand, to my neck, down my back, split and go down my legs!) I had seen a Neuro. and he diagnosed SI-Jt disfunction after an hour of examining me. He asked me to hop up on the table and drop my rt leg to the floor. Ouch! I saw a stellar orthopedist in Atlanta and he said SI Jt dysfunction was difficult to diagnose.

In Chicago again, knew better. shoveled for about 30 mins. the pain began in my hands and wrist. Went to ER. Tests performed. Saw top Neuro at Northwestern. Orthopedist. No diagnosis. But to me this sounds a lot like your airplane seat issue that has pledged you for yrs.

My body doesn't like to twist. And the shoveling motion was a twist with weight added. This was the beginning of strange nerve pains. But manageable. I was on the prednisone for months and the doctors allowed me to get off it on my own. I did, nerve pain gone!

Good luck.