I am 16 right now and I have been playing since I was seven. I am ranked and I try and play for about 2-3 hours everyday. I recently switched rackets from a Wilson Triad 6 to the Head i.prestige mid and its fine on my groundstrokes and volleys but yesterday on my serve I felt a twinge behind my shoulder blade. The pain wont go away and when a move around my arm I feel a small clicking(almost). Ive had shoulder problems before, but not in the back of the shoulder(more towards the front in the rotator cuff). Has anyone else had this problem? Or know of any solutions? Thanks.