Get some head and shoulders
Getting rid of cradle cap is not an overnight process, it takes a while just keep doing what your doing keep sheets clean, baby oil, brushing, as soon as she spits up get her out of it and wash head with soap and warm water. It'll go away soon.
You have to be cautious because it could be eczema. I've read a topic where it was said that eczema could be mistaken for a cradle cap. A medician examination may be needed, I suppose.
Here's the topic if somebody interested: https://easytobemom.com/baby-eczema/