Headaches??

I ran my first 5k of the year this weekend on a cool and cloudy day. I was hot as usual and no water was available on the route. I regularly get headaches at the very end or after a 5k route. The headache sometime lasts well into the day after the run. I drank 2 bottles of water after the race and made sure I drank throughout the rest of the day to make up any loss. The headache did not subside until I took some tylenol.

Does this make any sense to anyone and why?? It is the same type of headache I would get if I overexerted myself on a hot Summer day. I would have described this in the past like I was overheated.
I am running 2.5miles 3 times a week without any problems usually. This only occurs when I push myself as I did to finish the 5k.
Can you tell I am new to this whole exercise thing-LOL.
Thanks for your info
 

I get headaches when I workout hard or when it is very hot as well.   From my research I believe that the reason for this is that the blood vessels in my brain swell and that puts pressure on nerves, same thing they think that happens when you get a migraine headache.   I suffer from migraines so I am prone to get these "exercise headaches" as well.  For me the triggers are intense exercise where my heart rate gets very high, changes in weather pressure usually a low pressure system, dehydration, red wine, and a few days prior to my period.  I suspect that is what is happening to you.  As your fitness increases your heart rate will not get as high as easily and you won't get as many headaches.  The best way to increase your cardiovascular fitness is to pu**** so i choose to to it anyway.  You can treat these headaches well with a medication called Imitrex but it requires a perscription.  For some folks a strong does of caffine or Excedrin Migraine works well.  Hope that helps.

My guess is an electrolyte embalance.... Are you a salty sweater??? If so, you need to take in more than jus****er.... You need something with potasium, sodium, magnesium, etc.... Try Powerade Zero (I don't ike the taste) or tinker around with other sports drinks, but when your electrolytes are low, you can and will experience light headedness and headaches.... IMHO... Good luck././

Thanks
I am drinking some Powerade Zero today as it has been 2 days and I still have the headache mildly so I was thinking along these lines.
I have experienced a bit of light headedness also but I chaulk so much up to this crazy RNY and my reactions to different things.
Well I guess we just keep tinkering.