What Causes Discharge Of Large Amount Of Water From Vagina?

ive just had a big gush of water come out my vagina,i soaked my knickers so bad and left a big patch on my bed. im not pregnant nd i havent had sex for 3days,i cudnt even stop the water coming out. what could this be? any advice? im 25 yrs old, 2 kids,3 yr old and 3 months old,im british bangladeshi, 5ft.