You may be having alopecia areata. this is an autoimmune condition due to the attack of lymphocytes​ against hair roots. It results in the formation of bald patches on the scalp. It can affect any hairy area of the body also like eyebrows and  beard. It has to be treated properly for long duration until the immunity comes down. Once the immunity is controlled, hair grows back over the patches. Please call me or contact me with photos using online consult option for accurate diagnosis and treatment.