I hit my head on a ceiling fan last weekend but im just now feeling very painful headaches for three straight days. Could I have a concusion?

Concussion. Not likely a concussion. Headaches are usually immediate and worse with bending, stooping and exercise. There are too many questions required to determine the type of headache and a physical examination including the head and neck is important to make the diagnosis. Inwould see the medical doctor and seek a referral to a neurologist who specializes in headaches. .