Hand pain..??

[Rosie8]

There's a nerve that runs in that area. Some typical problems:
Gloves that are too tight or have a seam that hits that spot.
Gripping too tight (as mentioned above).
Flat bar handlebars with limited hand positions (as mentioned).

You might try:
Looser grip and shaking hands every "X" miles.
Looser gloves without seam on palm or wrist.
Ergon grips.
Different style handlebars that give you more hand positions.

I changed to tourist style / North Road style handlebars that sweep in toward the rider. My bike is a cruiser style with upright riding position which works well with this style. Good luck.