There are multiple causes for hair loss and a proper treatment can only be started after making a definite diagnosis. As you are having hair loss on face and scalp
and you have not mentioned any other preceding lesion, I presume most probably you are suffering from alopecia areata
where one gets single or multiple round coin like areas of hair loss. Sometimes it can be extensive to involve whole of the scalp or the body. As you have already consulted many dermatologists, it would be of importance to know what treatments you have taken till now so that a proper prescription can be suggested. At the same time, one should know alopecia areata has a remitting and relapsing tendency that is it can undergo spontaneous resolution only to recur at times later in life. If possible kindly send the photographs of affected area along with treatment taken so far,so that proper advise can be given.