Spot on arm

I know this is a period app, sorry, but I also see a lot of medically educated people on here- which is why I’m making this post.

Does anyone know what this could be? It’s been on my arm for 2-3 weeks. The red part is raised above the skin a little and feels bumpy. It doesn’t hurt or itch. It’s just weird it’s there. If it starts hurting or itching I will go to a doctor, but I was just wanting to see if anyone has had anything similar or knows what it could be!