Nappy rash cream

Hi mummy, may I know what caused this. I'm not sure is this diaper rash. But she been using this brand for at least 6 months. From size S/M to size L Recently find out that she has this. She is wearing size L now. And anyone can recommend good nappy rash cream to me? She never use nappy rash cream before. And should I change to another brand of diaper? Can recommend me as well please. Thanks. #1stimemom #advicepls #firstbaby #pleasehelp