oh my, that is no good!
Are there some crusty bumps and redness on her eyebrows? If so it could be feline dermatitis (I think that's what it's called), which can be caused by a lot of things - but if it's just her head, that could likely mean mites. I believe there are a dozern other reasons cats get this - like ringworms, fleas, infections, and allergies. I would bring a fecal sample when you go to the vet so they can check that, just in case.
In any case I'm no vet, but years ago one of my cats got this, was no real big deal. I believe his was a hormonal thing and we got some meds for it and it cleared up in time.
Best of luck to you and feel better Violaine