help! bleeding

So I'm five weeks pregnant. Lunch time today I had a brown discharge which eventually became red and now I've passed a couple of clots. I've got a doctors appointment for a scan tomorrow but what are the chances it's not a miscarriage. I'm 23 healthy, never had pelvic problems in my life. I'm freaking out people. I've read it could just be a clot or just bleeding and my baby could be fine. My mother in laws mum was bleeding for five month whilst with her. I'm preparing myself for the worst because I think I've miscarriaged but I just need someone to talk to xxxx