For the past week my son, who is 4 years

Patient: For the past week my son, who is 4 years old and has autism, has had extremely itchy feet when it is time to lay down and go to bed. He scratches and cries and it prevents him from falling asleep peacefully. It also wakes him up in the middle of the night and he cannot fall back asleep. There is no rash, nothing that looks unusual. I have tried giving him allergy medication, using anti-fungal foot spray, anti-itch lotion and oatmeal baths, etc. Nothing seems to help! Any thoughts?

Doctor: