My son is 7 years old. He has seasonal allergies and use to have asthma as a child. recently a rash has been appearing on his face, ears, neck, back, feet and knees. It itches a little. This happened before after a insect bite but only a few times. This past week they have been appearing suddenly while he is indoors. They look like little pimples and when I give him benadryl they vanish an hour later. We just moved from another state and I am in the process to find him a doctor and allergist. Should I be worried?