Sounds like a compression of some sort, such as blood vessels or nerve (try googling Thoracic Outlet Syndrome, Brachial Plexus Lesion, and Cervical Plexus Lesion). It could also be a trigger point aka a knot in the muscle, all trigger points have referral pains that can refer to other places such as the arm. But the numbess and blood rushing feelings sound more like either neurological or vascular compressions. I suggest seeing your doctor and have them assess you to pin point the root of the problem. If its a compression or knot, it would be best to see a physiotherapist of a massage therapist.