When I wash dishes my upper back feels very stressed. Could it be arthritis?

Another thing, I don't know if it's related or not, but I have a chronic itch right under my right shoulder blade. Initially I thought that it was my skin, but it feels deeper than that. I've wondered, too, if it's my nerves, but now I'm wondering if it could be my muscles. I can't seem to ever exactly locate the itch (only that it's under my right shoulder blade). When I scratch that area, it still itches like crazy. But it doesn't constantly itch. Sometimes it feels similar to a slight sunburn or abrasion (maybe even like a bee ******* under my skin, but without the pain...if that makes sense).

So my second question is, do stressed muscles itch when they heal?

Edit note: I don't know why, but "s-t-i-n-g-e-r" was censored.