Hi Eric, another one with shoulder pain also, felt like my shoulder was going to come out of it's socket. Helped if I supported my arm for a little while, especially if I was walking long distances. Excersizes everyone mentions above help, once the shoulder heals up some strength building exercises also, light weights at first.

Also, since you're a sports photographer and probably carrying a camera bag, you may want to consider what side of you're carrying the bag on. Used to use a backpack/breifcase/computer case, and like most folks, just slung it around one shoulder. Found later, after about 2 weeks my neck would feel exactly like it did when I had the first tumour in the nodes. Got worried, then realized what might have been causing it. Changed to a rolling computer case and didnt' carry over the shoulder, and pain went away. Don't know how you would deal with that in your case, (no pun intended).