Hello,
Bald patches on scalp may be due to 
alopecia areata, due to medication like Elavil (like in your case), androgenetic alopecia, tinea capitis or 
fungal infection of scalp, recovery from a chronic illness like typhoid, chicken pox, stress, lack of sleep, trace elements deficiency, psychiatric disorder called 
trichotillomania or hypothyroidism.
Though the list is exhaustive, your symptoms seem to fit into Elavil usage and alopecia areata. Discontinue Elavil and ask your physician for alternative drug, intralesional 
corticosteroids. Use Minoxidil 5% solution only on the areas of hair loss. Topical corticosteroids are recommended, Tab. Trichoton daily one for 6 months. If with the above medication, won't go, then you need to 
consult a dermatologist.
Take care. Hope I have answered your question. Let me know if I can assist you further.
Regards,
Dr. Pallavi M., Anesthesiologist