My husband was diagnosed in Oct/2009 with CRPS in his hand.

Around New Years he started complaining of a stiff shoulder. I nagged him to mention it when he went to PT but he put it off for 3 weeks until I finally went with him and asked them myself.

We were certain they would say his CRPS had spread, but his ortho diagnosed him with frozen shoulder and he started PT for that at the end of January. He has worked his tail off on his exercises and now has about 95% of his range of motion back.

So I would say, it certainly could be CRPS, but it's not necessarily that. You should get a diagnosis and some exercises to do on your back and shoulder. I truly believe that activity is key.

Good luck!