My new Tempur-pedic Pro Adapt Soft Is it hurting me? Help!

I just went through two Kingsdown mattresses in two months: awful, returned them. I’m 5 feet tall and weigh 118 pounds, petite. Can’t break in a thick mattress with coils, purchased a Tempur-pedic Pro Adapt Soft (the medium firm just felt too hard). Now I have rhomboid pain (between spine and shoulder blade) I read is probably referred from neck pain. I’m not sure if this is related to my new mattress, I’ve only been sleeping on it for 10 nights.

I just can’t break in any more mattresses! I’m over 65 and in excellent health, no arthritis, etc. but this is getting to be too much, I feel like I am in the Olympics! I have experienced this sort of pain before and it usually just goes away but this is freaking me out. The warranty is only 45 days (Raymour & Flanigan). My next and final choice would be a Sterns & Foster Cassat Plush, and that has memory foam and coils so here we go again. Can someone give me advice, I would so very much appreciate it. I’m in tears here! TY.