Please help! I can’t stop scratching all over!?

I’ve been scratching all oer (face, arms, legs, back, ears,) for nearly three days now. Everytime I scratch I get this horrible rash and it itches worse. I don’t know what this is. Chiggers or fleas maybe? It’s early in the morning and its gotten so severe I can’t sleep and I can’t get to a doctor until my parents get home tomorrow and even then I might not have time. So I need some relief fast. I’m scratching bloody holes in my skin and can barely take the itch, please help!
all we have for benadryl are these dumb little childrens tablets, im 16, will it still work?