Anonymous wrote:OP here. I think it's a nerve injury or a nerve irritation. I have issues with my neck/back and it may very well be something that is being pinched in my neck/back and traveling to my thumb!
It sounds like a nerve thing...could be in the thumb, via compression (you said it didn't bother you at all and listed all the things you did...might have irritated the area around it and it's inflamed). Do an experiement with ibuprofen and see if it goes away. if it's inflammation, then this product Relief Factor works great (it's just foods that reduce inflamation naturally, because it's bad to do ibruprofen or NSAIDS for long)
It could also be a nerve thing related to the spine. I had a spinal with my first C-section and they hit a nerve in my back. After that, I had phantom pain in my leg and big toe, which then turned to phantom itch. I had to remind myself that my itch was not a problem with my toe, it was with my back.