When I got to school this year I worked out everyday and I noticed that my forearms had red spots on them usually when working out and for a short time after (usually until I shower). These spots do go away, do not inflict any pain, do not itch, and are NOT BUMPS. They also appear very light and if I touch the skin it turns back to my normal skin tone kind of like a sunburn. I also have a pretty low sweat threshold and it's been pretty hot so I considered heat rash, but these are dispersed and flat unlike heat rash which was described as red bumps in small areas. I'm not very worried due to the lack of any bad symptoms, but I hope someone could let me know what it could be.