Sounds like a bacterial infection on top of the nappy rash (fungal). What have you tried? Are there blisters? Is the skin broken? Is there any crusting? Is there a white crusty ring around rashes?
- press rash with a clear piece of plastic (such as a plastic ruler). If skin turns pale - it is most likely eczema.
-Try giving a cool bath with QV flare up bath oil (not just the ordinary QV oil) twice a day. It has an antibacterial in it. should help with both eczema and infection.
- Nappy-free time is a great idea.
- Also try oats tied in muslin/hankerchief, soak and press over rashes. will relieve itching and redness.
- keep skin dry. avoid all heavy ointments and wash-off (rather than wipe) at nappy change
- you can try Dermaid soft 0.5% cortisone cream (very sparingly) over the worst "red" areas for a couple of days to help the rashes settle. Don't apply to broken skin.

HTH.