I experienced the same thing a year ago while diving in Cozumel. Both my arms and hands went numb, and I had the pins & needles tingling. I left Coz and returned to the Dallas area to seek medical treatment. Fast forward to today, I had three surgeries for carpal tunnel, cubital tunnel, and cervical disc replacement (ACDF). I cannot dive for at least another 6 months. If it is not a DCS hit, go see a good neurologist and get some testing done.