What could these bumps on forehead skin be that's not acne?

Contact dermatitis: Your skin may have come into contact with a substance to which an allergic reaction took place. It could have been a hat, a facial product, a hair product, or something that your hand contacted first, and then the forehead. There is also the possibility of a viral infection or shingles outbreak. It is best you get properly examined for adequate diagnosis and treatment.

Uncertain: This can't be diagnosed with the information that is available. A history, physical examination & other studies may be needed to determine cause/causes. Once accurately assessed a treatment plan can be developed.