I have in the past had extremely itchy skin without a rash or view able symptoms. My doctor gave me a possible solution. He had me use Fels Naptha soap. He said to scrub up with the soap all over then do not rinse off the soap. When the soap completely dries, turn shower back on and rinse completely. It took several treatments. It took at least 4 treatments but finnaly I had complete relief. He told me Fels Naptha soap was a laundry soap that did not have any perfume or any unnatural additives. Said as it dried it pulled poisons out of your skin to help healing.