Diaper rash?

Im a ftm so this may sound stupid, but my baby has been red in her diaper area since she was born (shes 2weeks old). I was under the impression it would lighten up and it hasnt, and now I feel like it might be diaper rash. Should i put anything on it? I thought we couldn’t put anything on her for about a month. We have been to the doctors 2 times (due to watching her weight) and they haven’t said anything… we go back tomorrow and ill be sure to ask but Id like to get ahead of it if i need to be putting cream on her.