Pain in the shoulder when doing handstand

Small update: I have been increasing the loads and the strengths lately. Eveything is going well.. if I have a massage every week or 2.

During the last month my massage therapist was in vacation so I skipped and the pain started to come back. She works always on a tight muscle under the front clavicula, almost on the neck, a lot of points in the chest, rotator cuff attachment on the back and the lower attachment of Latissimus dorsi muscle.

I have been doing the "arm underneath" stretch and it helps a lot for the upper back, but..

any suggestion on how to stretch the lower Latissimus dorsi muscle? thnx!

Every hanging position is potentially a stretch for the lower part, especially with a supinated grip and with a side flexion. The RC foundations course has some good ideas.