The pain you all experience is a temperomandibular joint pain, brought on by overactive salivary glands in your mouth (mainly the parotid). Wine has tannins, some individulas are ultra sensitive to these and their body responds to the taste of tanins by overproducing saliva very quickly leading to spasms of the muscles in the salivary gland and pain at the TMJ, spot just under the ear where the lower jaw articulates. Its much like the salovary reaction when you bite into a lemon, but even more rapid and powerful, thus the pain. 

This is most likely to occur with dry wines, or those that make you pucker as you sip.