Hi. I Have Been Experiencing A Red, Itchy Rash On

Hi. I have been experiencing a red, itchy rash on my elbows, arms, wrists, knees, and feet. My face and ears also become red.The rash occurs within 30 minutes of me waking up and lasts 1-2 hours. Then it goes away. I have been tested for allergies and tested negative for all food and environmental allergens. I was using an anti histamine and the rash still appeared.