2 days in a row i took a nap for two hours, and both times i woke up with a pounding headache. why??

Headaches: Hi andrew510, there are many causes of headaches(stress, infection, migraine, vision issues).Depending of the type of headache,I would be suspicious of dehydration.We lose a large amount of hydration during sleep.Most of the time we go to bed slightly dehydrated and wake up significantly so.Lack of sleep can also contribute(you are taking naps).Try to get a good eight hours/night.Hope that helps.