Please tell me it's not the MCNs...

I've been using cloth for about a month, all day with disposable at night. DD has developed a rash sort of like a bad heat rash mostly on her bottom cheeks and I'm really hoping it's a co-incidence as she's never suffered from nappy rash before.
Is there something I might be doing wrong that could cause it? She's not a heavy wetter and wears an average of 4 or 5/day between about 6.30 and 6pm. She does have nappy free time most days.
The only other thing I can think of is that she has been spending lots of time sitting in her sandpit which, atm, is often damp but I always rinse her off after and put on a clean nappy.
I am LOVING the MCNs and I would hate to stop. Any ideas or suggestions would be great.

What ones are you using? She might be sensitive to the materials (if they are synthetic) and not being able to use those particular ones without a liner or something... or is she teething? Getting molars or something?

I dunno if you are doing enough changes - I think we do about 6/7 changes during the day for both kids - and then into another for the night stretch...

She is in BBH AIO, GK funtimes and Ittis, sometimes with a flushable liner, sometimes without.
She definitely IS teething and now you mention it, her wee has smelt a bit stronger lately. Is paw paw ointment too difficult to get out? Perhaps the yellow one that's not petroleum based would be ok? Maybe a bit of a barrier is needed atm. :think:
I'll try changing more often too. Thanks for the tips!

You can use savlon for nappy rash with MCNs (that's the one that GK recommends)