Hello. So, about two or three days ago I woke up with a weird bump on my arm. It's sort of horseshoe shaped, it itches if I touch it, and it's raised and hard. It doesn't hurt, only stings the slightest bit if I press on it, and there are no others anywhere on my body. I've tried Benadryl but all it does is stop the itching for a little while. I posted photos on my profile, but it's hard to see because I have a large forearm tattoo. There are no heads on it, no puss, no bruising, or anything like that. It's just red. I was just wondering what it could be. I've looked into all kinds of bug bites, ringworm, and more and I can't find anything that seems right.