Is the rash a red spotty one near the top of her genitals? Only asking as my DD has the same and it won't go away either.
Do you think that could be thrush, Deirdre? I was told thrush can appear as a 'spotty', pimple-like rash. You can get it checked out and use an anti-fungal cream to get rid of that one. HTH a little...

ETA: Lee, pleeeeeease don't feel guilty We have levels of these bacteria on our skin aaaaaall the time, and every now and again, being the oportunists that they are, they break through our protective mechanisms and set up shop. It doesn't have anything to do with how clean or dirty we are - we just co-exist with these little buggers regardless. And hey, it may not be infected anyway. But particularly if it is a little weepy, it can't hurt to have someone look at it. (?)

And to the person who posted about poo-burn, I swear by the Herron Zinc & castor oil cream that someone else mentioned. Just make sure the bottom is dry and apply it EVERY nappy change and change nappy often - this is what we do when Natty goes on a poo spree. Honestly, some days that child will produce one at every nappy change! Like, every couple of hours! And they are done in total secret, lol. On those days I try to change her every couple of hours.