My wife got a terrible case of it a few years ago. She ended up going twice to different clinics for it. She was in misery for a month with it then it flared back up a couple times within the following months. Oatmeal baths did help in the short term along with calamine lotion. One doctor recommended Calmeseptine lotion I believe that's how it's spelled? Those also gave short term relief. They gave here first a series of steroid pills that didn't help then another clinic with the hospital gave her a shot and a stronger dosage of steroids that finally knocked it.
Speaking from extensive experience, if you're miserable I'd recommend seeing a physician ASAP who will likely give you a cortisone injection which typically provides significant relief in short order. The last thing you want to do is further compromise/irritate your skin with any concoction of harsh chemicals.