What does it mean if i can't raise my shoulder out forward or backward without it hurting badly?

It depends: These symptoms could be caused by many things, including a rotator cuff tear, frozen shoulder, or several other possibilities. I would suggest that you see an orthopaedic doctor asap in order to get x-rays and a physical exam.

Bursitis: At your age, and with no injury to the shoulder, it could be bursitis. See a sports medicine specialist, who can make the diagnosis for you.