Suggest Treatment For Small Red Spots On The Arm

I ve started to get red dots all up and down one arm. In the last few weeks I ve progressively gotten more, they re about the size of an eraser head and are spread out closer to my wrist but more clustered up to my bicep. I didn t think anything of them, they just looked like bug bites, but they are rather clustered and there are more than simple bites. They don t really itch unless I scratch at them a lot. Also, I ve had a couple spread to my neck, but again, just on my left side.