I'm nearly 12 weeks pregnant

So for the last week I've been developing this itchy spotty rash creeping up on different parts of my body, it's literally just itchy spots in patches, no actual redness or anything. No other symptoms just god awful itching.

I went to the pharmacy and they prescribed me hydrocortisone.. used the whole tube n it didn't go away

Went to urgent primary care in the hospital who said it looks like a heat rash due to the weather getting colder and having the heating on and obviously being pregnant makes my skin more sensitive.. prescribed me stronger steroid cream and e45 itch relief. This was only yesterday but I'm finding new itchy spots in new places..

I've had two other children and I've never had anything like this before, I know all pregnancy's are different, but has this happened to anyone else in first trimester? As even the doctors said the serious pregnancy rashes don't happen before 28 weeks. But I'm worried it is something serious n I'm just being fobbed off. I don't feel unwell or anything that isn't related to the pregnancy symptoms I've been feeling since I found out 😩 what do I do!!