all the suggestions so far are right on target - carpal tunnel, etc. - but I had a fingertip go numb on me for about a week - very odd - turned out to be a vitamin B12 deficiency. Vitamin B12 is an "energy" type vitamin - helps your metabolism, your central nervous system (not a weight loss or anything like that) - I now get shots once a month and take a daily B12 complex in addition to my regular multivitamin.
A true deficiency of this vitamin is not that common, but being low in the vitamin can also cause the same things such as extremity tingling, numbness, fatigue, etc. While you wait to see the doctor, might not be a bad idea to pop a few vitamins. My fingertip returned to normal within about 4 days of taking the vitamin. Good luck!