R shoulder pain, sudden, hurts in neck, can't lift it up foward or on the side.burning stabbing sensation. cant put much weigth on it. what can this be?

Tendonitis?: Assuming no injury. At your age it is probably a tendonitis. Treatment is ice and use of nsaids such as aleve (naproxen) . It is also possible to go to an orthopedist for a steroid injection.

Tendon or bursa: In someone your age with no history of trauma, a rotator cuff tendonitis or subacromial/subdeltoid bursitis. An orthopedic surgeon or physiatrist can take care of this problem, usually with a simple in-office injection of steroid and numbing medicine. If that doesn't help, an MRI may be ordered. Possible pt too.