Has this ever happened to you and should I see a doctor?

Today I was sitting in class. I'm on my period right now and so I felt like it was getting wet and going through my tampon.. Pretty normal. After class I went to the bathroom and I realized my entire butt was soaked through my pants and it wasn't blood, I think I literally peed myself and had no idea. I really don't know what to think because I'm only 18, not pregnant, I can't think of why this would happen. My mom told me to go to a doctor about it. Has this happened to anyone else before and what did you do? Should I go to a doctor?