Yeast diaper rash

My son has been diagnosed with a yeast diaper rash and the dr gave us nistantin and said use that along with aquaphor. Been using it for about a week and it doesn’t seem better, she said it could take up to two weeks.

I feel so bad for my baby because you can tel it’s painful. Anyone else experience this? Taking this long to show improvement?

Any suggestions are greatly appreciated.