What Causes Unbearable Shoulder Pain During Menstrual Cycle?

I HAVE UNBEARABLE SHOULDER PAIN,AND I NOTICE MY RIGHT SHOULDER GETS REALLY HARD AND I COULD FEEL A LUMP. THE ONLY THING IS THIS ONLY HAPPENS EVERY MONTH DURING MY MENSTURAL CYLE. I TRIED EVERYTHING AND NOTHING SEEMS TO HELP. CAN YOU PLEASE HELP ME WITH SOME KIND OF ANSWER??