running hangover?!?

froeschli

I started couch to 5k 2 weeks ago. am about to start week 3 tomorrow. i run one day, then take the next off. then go running again and so on.

what's bugging me, when i run and afterwards, i feel great, energized.
but the next day i get headachy and cranky. i first attributed it to PMS, but it's definitely a pattern, always the day after i go out running.

I eat my exercise calories, take a multivitamin, upped my protein and overall calories (1550). i drink so much water i constantly am looking for a bathroom (8 cups a day usually)....

it's currently about -5 Celsius out (23F), i don't think i get too cold while running, but that's subjective anyways...

any ideas on what could cause this? how to avoid it? it really almost feels like a hangover, just no nausea so far...