Based on your description, it sounds like a condition called alopecia areata.
With alopecia areata, you lose hair, usually in circular patches on the scalp or other parts of the body with hair. Autoimmune processes are thought to play a role. . The bodys immune cells, for no known reason, suddenly attack its own hair follicles. This causes you to lose hair.
You may lose a few circles of hair (alopecia areata). Or you may lose all hair on your scalp (alopecia totalis). In the most extreme cases, you could lose all the hair on your body (alopecia universalis). With any type of alopecia areata, you could also see nail changes, such as wavy contours and white lines.
There is no ideal treatment for alopecia areata. Topical steroid creams or steroid injections in the affected areas can help. Doctors have tried other treatments designed to slow the bodys immune response, but with little success. Hair usually regrows, even without treatment. But cycles of hair loss often happen again.
There are many other conditions that can cause hair loss. So see your doctor if you are losing hair. He or she will examine your scalp for any problems and talk over ways to help your hair loss.