What Could Be The Reason For Head Ache?

I was smoking and held my breath for too long a month ago, passed out and hit my head on the deck. The next thing I remember is sitting on the deck soaked because it was raining. My head ached a little bit but not bad, now almost a month later I get a severe headache that lasts only seconds after my heart race increases significantly, or lack of breathing (holding breath), the headache then resides into a dull ache felt through out the day at the base of my skull. Have gotten light headed a few times from standing up where I ve almost fallen over again. What could this be?