I have had this on my upper shoulder area...it would come and go...but yes, like you described...the skin is just sore to the touch.
I dont know the cause...but suspect it probably happens to a lot of people who simply dismiss it.
"Courage is not the abscence of fear, it is feeling afraid and doing it anyway!"
"Worrying does not empty tomorrow of its troubles...it empties today of its strength."
Corrie Ten Boom
Panic Syndrome recovery due to CBT