I HAVE A CONSTANT PAIN IN MY UPPER LEFT ARM,

I HAVE A CONSTANT PAIN IN MY UPPER LEFT ARM, BEEN THERE FOR 3 MONTHS, CERTAIN MOVEMENTS CAUSE MORE PAIN. NO INJURY I CAN THINK OF. I'VE GONE TO MASSAGE'S WITH NO HELP, ICE PACKS OR HEAT NO HELP. ITS REALLY NOT TENDER TO THE TOUCH BUT IT HURTS MOVE IF I START TO RAISE MY ARM, STRAIGHT OUT IN FRONT OF ME, OVER MY HEAD.
I'M 61, WITH FAMILY HEART PROBLEMS. I WORRY THAT BLOOD MY NOT BE GETTING TO THAT MUSCLE.