hi found you this info it could be this. exercise-induced urticaria is a condition that causes hives and other allergic symptoms. it can occur during or after exercise. hives or "welts" are usually raised flat bumps on the skin that are more red around the edge than in the middle. hives may also look like red spots blotches or blisters. they can occur on any part of the body. if so i would see your doctor. good luck
why do i get red spots on the edges of my lips after i've exercised? . i get a few red spots on the edges of my lips after i've done a lot of cardio and gotten really hot. it seems like they are in the spots where i have had cold sores in the past maybe where they have scarred or something. they pretty much only show up after a good exercise. on a regular basis and before exercise these spots seem to be less-pigmented (less lip-colored) like how tiny scars might look.