He seems to be having alopecia areata
. It is an autoimmune disease
where small round,oval, coin shaped patches of hair loss are seen. These patches may resolve spontaneously in some cases but may progress in some in terms of number and size to involve other hair bearing areas.
To treat the same, application of topical steroids like mometasone lotion daily or intra lesional injection of triamcinolone once in three to four week would help.
The bald patch of alopecia areata should be differentiated from fungal infection
of scalp too.
A consultation with dermatologist