I'm having my gallbladder out next week because I had similar symptoms, including the relentless itching. An ultrasound revealed gallstones and bloodwork showed my lipase and bilirubin elevated 10X normal. Dr. prescribed a Medrol dosepack which helped with the itching, but also my enzyme levels went back down.
About all I know is, skin itching can be a sign that the kidneys aren't working right. Toxins don't get cleared out of the body like they should, and they come out of the skin, and it can cause that annoying itching feeling.