What Can Cause Lot Of Water Running From Nose?

This is the third instance, where I noticed a lot of water running through my nose. It was as clear as water, little yellowish in colour.I have totally freaked out, though Iam to see a doctor in a day or two, Iam wondering,if this is anything serious.Iam not suffering from any disease, or allergy (asthma0 or anything like that.Today this happened to me around 3 am, when I was far asleep, and I got up scared, with water running out my right nostril (though the 2 revious times it was from my left nostril). After that I couldnot sleep with my left side of the brain on the below, I felt the same feeling (of water running down), so I had to sleep with my right side down.Please suggest !!