Hi Taz,
I had a "heat type of rash' that came up mainly when i went to bed....sometimes during the day if it was a hot day.
I had it for 6 months straight every single night (7 weeks before due date now) and used to get up and put ice packs on the hives and rub an aloe vera plant on my skin afterwards. This only helped midly.
I changed my diet and stopped eating "heat related foods" and stopped buying instant food to avoid the preservatives, colourings etc.
What it ended up being was the pregnancy vitamin I was taking as within a week of stopping it, my nightly rash had diminished to about 2%. Obviously there is something in the tablet that affected my system and came out at night to haunt me.
Hope you find some relief soon.....
Bianca