Rashes and bathing

Beebee

My baby's got yellow crust behind the ears that smells bad and crust one side outter corner of the nose. Been treating it with warm water and olive oil. Is that ok? Should I use salin or will it irritate it?

Past 2 days she's also developed rash looking on her ears behind the neck and started up back of her head.

Should I bath her with mild baby shampoo at 5 weeks? Been only bathing in water.