D.T.
PUPPs usually doesn't develop post-partum - it's normally during pregnancy. Once you have it, you are FAR more likely to get it during future pregnancies. You can take steriods (a very mild dose) daily to get rid of the symptoms while pregnant. PUPPs won't actually go away until you give birth, but the symptoms (insanely itchy red raised rash) will subside.
Did your dermotologist actually do a skin biopsy to study the rash the first time to determine it was actually PUPPs. Most docs do not do this and just guess. There are MANY 'pregnancy rashes' that look just like PUPPPs but are NOT PUPPs. I'm thinking this may be the case because the odds of developing PUPPs after giving birth are extremely low.