Shoulder pain

A few months ago I hurt my shoulder by over-stretching on a punch. I felt something tear/pop behind my shoulder blade. After that whenever I did anything with my shoulder or arm I would feel it go numb and have a feeling of ice run through my shoulder and arm as well as the area around the shoulder blade. My doctor found nothing wrong and there was nothing in the x-rays. I took some prescribed anti-inflammatories and did nothing for two months and the numbness went away. I still feel an ache in my shoulder and tricep, however, whether I'm exercising or not. If anyone knows of some herb or something I can use to alleviate the pain I would be very grateful. Oh yeah, and if you also know of some herb/ exercise I can do to keep pain out of my knees I would be even more grateful! Thanks :confused: