I had been ignoring the rash. I thought it was from the Aspercreme that I had slathered on my shoulder (in case you are in a similar boat and thinking of trying it, I should mention that it did not help).
The rash got worse. As it did, the pain moved out of my bones and joints and gathered itself in the skin around the blisters. Some of the blisters started to get crusty, which made me think of chickenpox.
That’s right: the Invisible Box of Pain is full of herpes. I guess I can cancel the physical therapy appointment.