Could be a couple of things.


Teething? regardless of your nappy this can cause a rash.
She may be reacting to the inner of the nappy- people sometimes have issues with one sort of fabric or another. Mostly it is synthetics that cause issues but not always. What nappies are you using? You could try a silk liner which combats a lot of reaction issues for people.

You can still use a cream, but if you use a water based one it wont clog up and ruin your nappies. I use Moo goo soothing cream which clears up most rashes no prob. If we have a super nasty one for whatever reason, which we have had occasionally, i either put a girls in a disposable for a couple of changes and slather the cream on, or i use liners to protect the nappy.

Don;t despair, this is fixable!