Mountain sickness in denver area. help?

Rest, hydrate &...: If possible going to a lower altitude is one of the best solutions. Otherwise, minimize activity until you are more acclimated. Drink plenty of water. If you begin to feel really bad, you may have to go to the er.

Altitude sickness: can be prevented by pre-medicating prior to your next trip with an agent like Diamox (acetazolamide) which shifts the Oxygen-Hemoglobin dissociation curve. Hydration can help to some degree. I wish that somebody had told you to pre-medicate prior to your trip. I hope you take lots of photos so you can recall more than the headache you no doubt have.