I have one of these clear hard bump on my thumb right where the thumb bends. It has a head onit almost like a whitehead pimple.

Dyshidrosis? This may be a form of eczema that can be brought out by allergy, stress and environmental exposure. Read about it online - verify by viewing online images and read about symptomatic relief. See a Dr if you need a Rx.
Bump on thumb. One POSSIBILITY is that you have a cyst. Please see you doctor. He/she will diagnose and perhaps drain or remove it. Peace and good health.