For about 2 years now I've had this undiagnosed problem where my body gets itchy when I'm warm, exercise, showering etc. Doesn't matter if I'm wearing any clothing or not, it's the heat that triggers it. It could be anywhere and it goes away if I scratch it. I have taken a general allergy blood test but nothing can of that. Every day I take 10mg of allergy medicine and it does help but doesn't remove my symptom completely. Once the allergy medicine runs out, the itching comes back in full force. There are no visible rashes anywhere.