Answer:
A dermatologist
Explanation:
A person goes to a neurologist when she is having problems related to the head or the brain.
A person goes to an otolaryngologist when she is having hearing problems.
A person goes to a dermatologist when she is having skin problems.
A person goes to an ophthalmologist when she is having vision problems.
In this problem
John's problems are related to the skin. So he goes to the dermatologist.
