Right shoulder pain any help?

my shoulder has been hurting real bad lately. im 15. i am active i wrestle alot and im in muay thai kickboxing. for about a month now my shoulder has been hurting off an on. but this time, it hurts pretty bad whenever i move my whole arm in a certain way. it hurts right on the outside of my shoulder and its hard to explain where but it seems like its at the part where my arm and shoulder come together on the right side of my right shoulder