Try taking some supplements for nerves and muscles - Calcium, Magnesium and Zinc are usually sold in one tablet. Exercise your fingers and thumbs every day as often as you can. Squeeze a small rubber ball and rub the area between your thumb and finger. - Hope this helps.
It might be nerve damage, i would see a doc just to make sure, I would bet it is nerve damage , its nothing serious , but u might need physio therapy , i hope that helps