Why does my right arm and hand get numb even when im not doing anything.?

Numbness arm & hand: What you're experiencing indicates a nerve problem arising from compression or impingment arising either in your armpit or up in the neck. Consult a neurologist.

Pinched nerve: Based on your symptoms this most likley a condition called a cervical radiculopathy. This is a pinched nerve in the neck that can cause numbness, tingling or both in the arm. Initial treatment can include physical therapy and oral cortizone (hydrocortisone).