Hello. My GP (in the UK) diagnosed my shoulder pain as "frozen shoulder" about 6 months ago. I had been experiencing pain and limited movement in the upper arm and shoulder for a few months before that, possibly triggered by a fall off my bike onto the arm. I also asked my GP about redness in one armpit (the same arm) and he could not connect the two problems.
I have had a few sessions of physio, but no marked effect, so now I just do some exercises 2 or 3 times a day, and I feel that there is a gradual improvement, particularly as I am feeling less discomfort at at night.
I would be interested to hear whether others with so-called frozen shoulder have experienced the armpit redness problem. If so, has their condition been diagnosed more precisely than FS. I would not call it a rash as it is not itchy or painful.