Somebody chucked a snow ball at my head and it hurts. i have a head ache now. could i have had a concussion?

Maybe: Hello. Symptoms of a concussion can include: headache, nausea, vomiting, confusion, blurred vision, slurred speech, weakness, feeling dazed, numbness, lack of coordination, problems with short term memory, dizziness as well as repeating things over and over. You can develop a concussion with or without loss of consciousness.

Not headache alone: Headache alone does not define a concussion. If yoiu do not have other symptoms such as confusion, disorientation, unsteadiness, etc. you did not have a concussion.