Did i mess up my shoulder please help?

Ok so around 2 weeks ago i think i may have injured my shoulder. I woke up in the middle of the night and wanted to turn on my fan. The fan was behind me cause i was turned to the other side so i reached with my left arm an tried turning the little circular thing to turn it on and when i turned it i felt a really sharp pain near where the arm and shoulder connect. It only hurts with certain movements like when i try to lift my arm up or extend it. Also i twisted my arm inwards like towards my stomach thats when i felt the sharp pain. So i need some advice on whats going on its stiff an painful every morning i wake up and would really want to know if its serious