Hello,
The symptoms are suggestive of tinea capitis. The symptoms of Ringworm or Tinea Capitis include a dry itchy scalp, scaling, crusting, inflamed nodules, hair loss and tender enlarged lymph nodes on the neck. Diagnosis is by clinical examination of the scalp as well as a skin lesion biopsy with microscopic examination. Anti-fungal medications, taken by mouth, are used to treat the stubborn infection.
Please get this examined and a KOH examination of the skin scrapings done from a dermatologist.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
I'd check him for food allergies. You could do this by just eliminating the common allergens and see if he improves - soy, dairy, wheat,, nuts, peanuts.
I'd try Nizoral shampoo, also.
Selenium sulphide while is good for seborrheic dermatitis could well cause an irritant dermatitis in some.Your doctor will be adept in handling, by giving hydrocortisone creme if he deems it fit.