Soupkitchen - went to the doctor this morning with DD2. Reasons for going have changed a bit over the week since I booked the appointment. Started as 'Does DD2 have thrush because she can be a bit whiffy and I thought that meant it wasn't thrust?' and then moved on to 'I think DD2 has threadworms' .
In any case, there is a possibility that DD2 might have thrush or something which I've been struggling to remember (too much smiling and nodding at the doctor ... I have a very annoying tendency to do that) - but it essentially meant a swollen and red front bottom. The doctor took a swab (not internal thank god) and will get back to me. However, because DD2 HAS got threadworm, the doctor's treating that first and not anything else because she thinks it might all be connected.
The bit that's relevant to you (once you've waded through all that) is that when I mentioned the smell she said she wasn't concerned about that at all. If we were following all the usual hygience measures (wiping front to back), washing hands etc. and there was no discharge then keep your DD as clean as you can but don't worry about it too much. She said it might be a bit of unwiped pee or some such thing. Don't use soap - she prescribed us Oilatum for the bath (and both DD's skin felt really lovely for it afterwards too).
Sorry that's not 100% thorough and that I've taken a while to revert but I've been washing, washing, washing and doing yet more washing (of bedlinen, towels etc.) today and I'm knackered!
Thank you for your help everyone, I really appreciate your ideas, guidance and experiences ... it's not a topic I'd raise in 'real life' and it's been brilliant to have all this knowledge pooled here. Thank you.