Positioning can help. I got tingling, numbness, pain etc and the doctor prescribed ibuprofen, rest and ignoring it. (The same guy advocated ignoring palpitations before he saw my ECG printout.)
I get wrist pain when I use a desk or table, particularly if the chair-height isn't compatible with the desk height, forcing wrist-up position. My best writing position is sitting center of sofa with back fully supported and netbook tilted away from me (downhill to knees) so wrists straight or slightly curled inwards. Second-best position is half-reclining on pillows on bed (netbook sloping away). I use a photo album or ringbinder as a desk.
Two-finger typing is better than touch-typing too, because I use mainly the middle fingers and don't spread my hands. Try not to press on the little fingers (pinkies?) especially when stretched.
Writing longhand is better slow and with a fine free-flowing ballpoint, a gel pen or a properly-sharpened HB pencil.
Anyone who's having pain in their neck might want to adjust their writing position, too.

OT. Does anyone know a writer with visual impairment? I have a colleague who's having trouble editing his creative writing because he can't read it back and his wife reads with different emphasis.