I Have A Chronic Full Thickness Tear Of The Supraspinatus

I have a chronic full thickness tear of the supraspinatus tendon , Enthesopathy of the infraspinatus tendon, Moderate arthropathy of the acromiolavicular joint. I wanted something to apply to ease the ache in my shoulder. I have had a mitral valve prolapse since birth and am under a Cardiologist at a top Brisbane Hospital. I am 81 years of age and still active. This is my left shoulder and I still tenpin bowl, which is out at present. Why shouldn't I apply Nurofen Gel? or is there some other way to relief the pain which makes me feel sick and is very tiring.