Hi and welcome!
Can you be more descriptive or provide a picture? My first thought is that you may be seeing new feathers growing in on the forehead. New feathers are blood feathers, meaning they start out filled with blood and on the forehead you'll see dark red dots or "pins" as we call them. Over the course of a few days the blood will recede (you'll be able to see it) and the new feather develops a waxy coating of keratin and the feathers look very spiky. Once the blood has receded the new feather is broken free when the bird preens or rubs their head on a perch or toy.
Does this sound like what you're seeing? I know that seeing new pin feathers on my budgies' stark white foreheads scared me the first time I saw them!
