What Causes An Itchy Skin Rash Along With Heart Palpitations And Fatigue?

Symptoms started over a year ago with a itchy rash on the head first, then spreading off and on throughout the body, has seen a dermatologist without much help with topicals and allergy medicine. Next symptom started about 6 months ago with high blood pressure (now better controlled with no medication) but suffering heart palpitations daily and new symptom within the last 2 weeks of a daily headache, fatigue, nausea. Doctor seen and said it was a virus, gave him nose spray for sinuses. Still suffering and now affecting daily life. Mail-away stool studies showed a problem with pancreatic enzymes, but blood tests came back normal and did not support this. Unsure of the all the other blood tests that were done, but basically they could not find anything.