I hit my head today on my a.c vent trying to get up from picking some thing up earlier and i still have a headache ?

Haedache: You could have bruised the scalp, it might be sore for few days. If you have any associated visual changes or develop any nausea/vomiting, have it examined by a physician.

I'll bet!: That definitely hurts! As long as you were not knocked unconscious and you don't have nausea or vomiting, the headache is to be expected. If you develop any nausea/vomiting, numbness/tingling in the hands or feet or if the headache becomes more severe, go to the ER.