Middle school daughter's acne concerns

My middle school daughter has a lot of small pimples on her forehead, and even though she manages them at home, they come and go.

I use a face mask every day, so what could be the problem?

I guess I'll have to go to a dermatologist and spend some money.

Does getting treatment at a dermatologist definitely have an effect these days? Or is it just temporary?

I'm conflicted.