I'm having trouble with cotton mouth/dry throat on my runs. I've been drinking at least 3 liters of water a day, no alcohol, and only one cup of coffee in the morning. Still, on my runs, I'm getting really dry throat, and end up having to spit a lot. I live in Oakland, CA, and it's been a perfect 60 degrees most days. Been living here more than a year, so I should be acclimated. Whats going on?