@matigo Massage in the correct area is usually effective as the pain felt is reflected pain. There's a spot at the front of the shoulder midway inline from the collarbone to the armpit where there's a cluster of tendons just below the skin. My shower-head has a massage setting, I've just used that to massage the tendon area, seems to have helped a bit.
I'm about to tackle that massage job, using some diclofenac NSAID gel.