Just as an update, my rash got a lot worse and so I have a doctor's appointment on Tuesday. Two pharmacists have told me that they think it is hormonal and today I've got some brown spotting, 40 days after my last period. Rash feels a bit less angry today - anyone had anything similar and found anything that works well. I'm taking piriteze and using e45 and Eumovate.
As an aside someone put it into my head that it might be bedbugs and because I am pretty anxious before a period I took it to heart. I wonder where the old, sensible non hysterical me has gone to sometimes.