Please help! Im desperate!

So for about a year and a half maybe 2, i have been experiencing something horrible, every single day i will get a discharge and its like white or clear and it makes all my underwear horrible, i often have to wear a panty liner every day, and its horrible at school. Its like im constantly wet. sometimes its so bad i worry it has gone through my trousers, i want it to stop. What is it?!