Hydration is a must for anybody ... smoker, non-smoker, or vaper ... I felt a lot of those types of feelings in the beginning. I'd say the majority of it was the withdrawal symptoms from stopping smoking, but I don't want to discount hydration. You can over-hydrate, but I'll skip that for the sake of the conversation, and just leave it with the fact that if it's dark or clear coming out, then it's not good ... dark = need more water, and clear = cut the water a hair.
The withdrawal symptoms lasted for about three months for me (your mileage may vary.) After that, it was more about the diet and exercise I had in my life. I became far more active once I could actually breathe again, and that was another factor that called for hydration. I stopped being a smoker at the end of this month in 2010, and I am extremely happy that I found this world and ECF!