It's very difficult for me to raise my arm above my head on its own.

Doctor can examine: If an arm is hard to raise, falls asleep, or goes numb and tingly, especially in certain positions of the arm, there may be compression of the tendons or nerves related to that arm. A primary care doctor, orthopedist, and physiatrist (physical medicine & rehabilitation doctor) can help figure this out. Sometimes MRI or x-rays are done to look at the inside of the shoulder.