Terrible headaches I need advice

I have been having these absolutely terrible headaches Lately. The first day I had one it felt like some one was hitting me in the head repeatedly all day it was really hard for me to focus or do daily activitys. Today it came back but it was off and on. Trust me when it was on it was terrible. Should I be worried? I haven't ever had a headache this bad. Should I see a doctor if it continues for a third day?