What Causes Itching Sensation On Scalp And Ears?

My head started itching a few weeks ago, two weeks ago I started having issues (once a day when I ate with stomach nausea although I never grew up and after it passed I was fine the rest of the day to eat or drink) no other flu like symptoms and My activity was normal including my daily exercise regiment. Now my head an my ears are itching and I had hives yesterday morning on my inner thighs, calves and uderside of my arms... I started itching a bit and went for a run after which I completely broke out into a rash in those same places. I took a benadryl and the rash calmed down although I still have spots and I still itch. Im 47, in very good shape, 5.5 and 135 pounds, a very healthy eater, could probably drink less. I take synthroid every morning for Hypo and I had a very small bout with bladder cancer a few years ago which was able to be blasted out (stage 0). I dont have lice... i went to Urgent care yesterday and she checked for signs of Scabies...nothing and they were stumped...any thoughts? Maybe the itching and the gut issues are not related but it sure seems like they might be