Oh M., you poor poor thing. My heart also goes out to you. I had a raging case of PUPPPS during the last few weeks of pregnancy with my son. It spread to my arms and legs and was just absolutely awful. I tried dandelion root and nettles, but neither really made the difference. The doctor had me take Benedryl at night to sleep (which only helped for about 3 hours of the night) and told me to use Sarna lotion. While the Sarna worked at first, I found myself putting it on constantly. I think I'll cry if I ever have to smell that again. Anyway, it got so awful and I wasn't sleeping at all, so the doctors (who initially didn't believe that I had PUPPPS, even though I had come to that diagnosis) finally put me on prednisone. I initially didn't want the steroids out of fear for the baby, but oh heavens did it help! They were gone within a few days of taking the steroids and I could finally sleep again.
One side effect of the steroids, by the way, is premature leaking of fluid or rupture of membranes. My fluid started to leak at 39 weeks, and they admitted me that night. After 40 hours of unsuccessful labor (complete with pitocin and the works) I ended up with a C-section. I have no idea if the leaking was from a normal rupture or a premature one from the steroids. Either way, I still think the steroids were worth it - PUPPPS is just about the worst thing ever!!!
Also, one thing that helped me get through the day at work with this rash was ice packs!! I got a really big ice pack from the drug store that lasted for quite some time. You can even strap it to yourself with a handy dandy little case. I would buy two or three and rotate them throughout the day and night to get some relief.
Best of luck to you M.,