Rash. Help!

I just started my son onto cloth, I've been anticipating this day for so long because with PPD it wasn't happening!

We started two weeks ago and after just three days he started getting horrible rashes. This NEVER happened with my daughter. We switched him to disposables 2 days ago and it's already looking better. What am I doing wrong this him? I'm using creams, i use the same soap for his clothes so I can't imagine it being that.. Please help I really want to get back into our cute cloth!