My Son (13 Years Old) Has A Large Patch Of

My son (13 years old) has a large patch of scabs on top of his head. It seems like it might be seborrheic dermatitis but it is not itching him that much, it's just a whole bunch of scabs, mainly on top of his head but it seems to be starting on the back now. He is playing football now so I assume it is from his helmet? I can't seem to get it to go away, I've tried T gel and other types of those products.