My 7 year old son has a rash around ear and it's itchy and wet inside of the ear. what is this?

See Your Doctor Now: There can be a number of causes for symptoms described including infection, allergic phenomena, systemic illness-related, and more. Additionally, crucial information is lacking such as: duration, precise description of "rash", recent illness, past medical history, and more. Be aware: diagnosing rashes is challenging without visual inspection. See your doctor now for prompt and correct diagnosis.

External ear : Inflammation, could be infected, a fungus may be, will need to be seen by his doctor, can't really help you much without more history and physical examination, best wishes