Throwing up out of no where?

Last night I went hiking with my friend. We were hiking for about 2 hours. (1 hour in and 1 hour out.) it was about 7:30 so it was nice outside. Not too hot and not too cool. It felt good out. Anyways, once I got home it was almost 11 o'clock. We got don't hiking at 9:30 and then I has to drive her home and then drive myself back home. Once I got home I had such an awful headache (yes, I drank lost of water on our hike.) and it progressively got worse. About 11:30 I felt the need to throw up and that's exactly what I did. I thought I would be okay and laid down in bed with my fiancé. About 10 minutes later I felt the need to throw up again! And as soon as I got up I started gagging and almost didn't make it to the bathroom. My stomach is still feeling very queasy this morning every time I stand up or walk around. My question is: Do I feel this way because of the headache I had last night or is it something else?