The spasms could be pulling upwards, have you had anyone try to press down on your top ribs? called top rib or first rib mobilization.. rib mob for short..
and check for trigger points too. ( do this part first) then rib mob..

usually the muscle tenses, and continued tension creates trigger points -knots in the muscle - those need to be released before the muscles can fully relax.

There's videos of top rib mobilizations & trigger point info posted in threads recently as well as the sticky threads..


Are your shoulder level/even, many of us have uneven shoulders...