I get issues in the same area. I often use a lax ball either lying on ground, or standing against wall. I would look at all relevant structures such as lats, pec’s, levator scapulae. etc. Pretty much anything to do with scapula, get length back into. It could be fascial restriction with nerve entrapment if it’s not residing. Need to break down any and all adhesions in area. Just my two cents.