I hate to be that guy... if you have a straight bar, consider switching to a swept bar. You'll be able to use the same controls, and while it only offers one hand position, it's a much more comfortable position.

With a straight bar, I'm in pain by the first half mile. This is why you see people installing bar ends or riding with their palms cupped over the ends of their bars, or their fists on top of the bar. With a swept bar, I can ride indefinitely in one position. That bit of rotation to the wrists makes a huge difference.

Otherwise, raising the bar, and considering a drop bar, are also possible solutions. It's also cheaper to try a swept bar since you can usually use the same controls and cables.