My 5yr old son has a rash that started Monday in his,armpit and on his side. They are small skin toned bumps. We have been giving him Benadryl and cortisone cream for the itch but its has spread. It not cover his abdomen, sides, both armpits, behind his arms and behind his knees. He hasn t had a fever, the rash isn t blistered or crusted. What should we do?