Suggest Treatment For Discomfort In The Shoulder Area

i am 69, 5:10 , 155 lbs, have gastritis, hiatal hernia and am taking one 20mg omeprazole tablet/day. all under doctors care and diagnosis. i had an upper endoscopy may 2010. an exam, mri, xray, etc. by an orthopedic surgeon last fall showed i had to cartilage in my left shoulder socket. i chose pt rather than a shoulder replacement at the time. therapy improved my limited range of motion, lessoned the pain but a week ago i had a setback while reaching for my autos driver side door handle to close the door. felt something snap in my shoulder, could barely move my arm. today i'm going to see my primary care md for a post er visit followup. had to go to er on 5/29 in desparation. is instaflex right for me? have been taking GS-500 by enzymatic therapy stable form 1 capsule per day for 17 years for other aches and pains. work out daily on exercise bike and bowflex. have worked with free weights etc. since age 15.