I am 27 years old. And have sustained no serious injuries that would lead up to what I'm experiencing now. I was surfing a few days ago for about 4 hours non-stop. At about the 2-3 hour mark, I began feeling some discomfort in my back, near my left rib cage, but behind a bit (or so I believe). I immediately assumed it was just sore muscles from paddling/holding my head up with my chest flat on the surfboard while paddling. I continued surfing, knowing that I may be sore tomorrow, but with the attitude that "it may be worth it today". I used some chinese cupping therapy on my back that night in hope of loosening up the tightened/sore muscles. The next day, my back was in much more pain. A day later, the pain had spread to a spot near or within my left rib cage (hurts to cough, move in certain ways, etc.). Please advise. Thanks!