I've been riding my new bike a couple of weeks and have been having pain at the joint where the thumb meets the hands. The pain is especially bad in the morning on waking up. This is a big problem since I'm a professional pianist. I'm so excited about cycling but absolutely cannot afford to hurt my hands.

So, I'm riding an IBEX flat bar road bike with rapidfire shifters. I have played around with the angle of the brakes and shifters a lot, but somehow I don't think that's the problem. I think it comes from just holding the bars. I have bar ends too, which definitely feel comfy.

Any experience or advice with thumb aches like this?