I had this too. Or at least I thought I had.
It started about a week before I went into labour. Also started around my belly button and then my wrists and ankles. During labour it really flared up and gradually got worse over the next couple of days until I was covered in huge blisters all over my body except the palms of my hands, soles and (luckily) face. I'd had a CS and could hardly move but I had to change bedclothes often as all the blisters were weeping continuously. They took me to a specialist dermatology hospital, did a couple of biopsies, had dozens of students filing in to look at my swollen body, got asked a million times when the baby was due ('she's two days old, thank you') and was diagnosed PG, although a couple of weeks later they said the analysis for that came back negative so they were at a loss for what it actually was.
They gave me sulfate something or other to put in the bath to soak in for 20min every day to dry out the blisters. Then I had to use a steroid cream, but they were reluctant to give me oral steroids because I was breastfeeding. It took a couple of weeks for the blisters to disappear (they were amazed I didn't have any scars after all that) and all in all I was clear within 4-5 weeks.
I was told that if it was PG I would get it again if I went on the pill or had more pregnancies. I tried to go on the pill a year later and the itching started badly so I stopped immediately. I then got pregnant twice more. With the second pregnancy I knew I was pregnant just becuase my legs were itching in the same place again, but luckily that subsided after a few weeks, flared up again around 19 wks and just before going into labour but it never got bad. With the third pregnancy I only got a bit of itching now and again but was pretty much under control.
You really have my sympathy. Even though the CS was bad, I thought the whole PG drama was much worse - it was taking me around 2 hours a day to put all the creams on, do the soak in the sulfate stuff, etc. The combination of that and a baby that screamed non stop was no fun at all.