We had been fighting Alana's nappy rash from 3 weeks until about 6 months. It sounds as though bubs could have a fungal type problem, which seemed to be Alana's problem all the time. Its been so bad that she has been on antibiotics twice for it.

What helped was using a anti-fungal cream, like canestan and then putting curash nappy cream over the top. We did the canestan twice a day for about two weeks. Now we use Daktozin, which is fungal cream and zinc cream together once a day with curash nappy cream. We also changed her nappies to Huggies as we found that they were much softer and we only use non scented wipes (curash-they are very soft wipes). Thank goodness she hasn't had a flare up for two months.

Hope you find something that works.