When I have fast changes in heat, or i get to hot or anything like that, I get this bright red patches all over my stomach and back, and not a little it covers my whole stomach and back, and it always itches really bad but it dont stay it goes away in like 5 min after it comes then about 20 min the res patches disappear.. What is this, You think it something serious? SHould I go to a doctor or is it something that will work it self out?