If you have any type of cubital or carpal tunnel isses that can be contributing too. I've been suffering from terrible hand pain in my right hand ever since I got my flat bar road bike. Tried bar ends, that helped but didn't solve it.

Last week I finally ordered a pair of the Ergon bar grips. I switched them over and Mondays ride was the first ride in months that didn't end in pain and with my half of my right hand being numb.

Definately something to consider.