Feel hungover- zero alcohol!

Erin
So I have not drank one drop of alcohol since we started trying in January. I am only 4w 2d today. I don't really have symptoms - except I'm pretty sure my prenatals are making me constipated and giving me gas. Anyway, every morning for the last four days I have woken up with that cotton mouth cotton filled head feeling you get when you were out too late and drinking too much. With alcohol I know it's typically caused by dehydration, but I'm drinking SO much more water in the last two weeks on purpose (like at least 10 cups a day- I'm tracking it with that being the goal). What gives?!