Sudden pain in rt upper outer arm about 4 inches below shoulder. pain only there when i move my arm in certain directions. weakness in hand and wrist?

Neck: Likely radicular nerve pain from nerve problem in neck. May or may not have neck pain associated. Follow up with pcp or ortho for work up

Arms are innervated: by spinal cord roots C3-T2. Sudden pain is worrisome, but wrist & hand weakness is even more concerning. Your doc needs to obtain brain & C-spine/upper T-spine imaging *now* to look for either a central or peripheral lesion, especially if this is your dominant hand. Don't sit on this. X-Ray series plus MRI/MRA.