How do I treat a nappy rash?

My baby girl has the worst nappy rash. I think she's teathing but I'm really concerned about it.. She has a very fair skin and has a dark red rash. She also has a bit of diorrhoea.


Best Diaper Rash Cream?

What is the best diaper rash cream? Already tried Desitin with no improvement at all. This is the worst I have ever seen, her poor little bottom is bleeding.