What causes shoulder pain and finger numbness? the pain is really bad and my arm is almost immobile.

Arm pain: The most likely cause of pain and numbness in an arm and shoulder is from a nerve. This could include a nerve from your neck (radiculopathy) or from the upper trunk of the brachial plexus (brachial neuritis).

Shoulder instability: Due to a variety of causes, previous trauma, muscle weakness or injury. Loose ligaments are some causes. An unstable shoulder can give a feeling of apprehension when in certain positions and make the arm feel " dead". There are other explanations too. See an orthopedic surgeon . It's not normal for a 22 year old to feel this.