Hi.. Thanks for asking Health care magic... Muscle spasms can be seen in many systemic diseases and nervous disorders.. But they are not routinley presesnt with muscle spasm.. So first thing is you have to rule out simple conditions of muscle spasms.. -Over usage.. if you are doing new strenous work it may be cause of spasms -Dehydration can cause spasms Solution: Drink plenty of water specially before any physical work, do muscle strech exercises for muscles around shoulder by consulting an expert or observing youtube videos..take carnitine supplements for muscle health.. for pain relief you can use combination of pain killers with muscle relaxants [ex Zerodol MR] If condition isnt resolving with above measures you need to consult physician for further evaluation.. Hope i clarified your doubts..