ok, since you're going in for a fit, there's not much point in asking for internet tips.

but: consider these possibilities and discuss with your fitter:
- what's your day job - are you prone to carpal tunnel-ish stuff anyway?
- what's your overall body fitness? maybe some pushups and core work is in order?
- and yeah, it could partially / largely be a case of "new bike high mileage syndrome"

Good luck.