What Causes Clear, Odorless, Non-sticky Fluid After Extreme Pain In Uterus?

I am a 31 yo female and twice i have woken up to find my bed soaked by a clear, odorless, non-sticky fluid that completely covers my clothes and bed. I know it's not urine or vaginal discharge. The night before it happens I tend to have extreme pain in my uterus, like menstrual cramps, but worse. What is this and how do I stop it from happening again?