Its probably a bit of thrush as well Linda. I use Dakotzin(sp) on Gemma its like sudocream but a bit thicker and has anti-fungal cream in it. A few of the girls from BB recommended it and its fantastic.
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We use this too, cleans up even the worst nappy rash in 24 hours or so I love it.
Definitely sounds like you need something with an antifungal.