Freaking out!

So I am 4 weeks, 3 days today and have had light bleeding since this morning, mild cramping and just passed about a quarter-sized clot. The bleeding seems to have subsided since the clot and the cramping is now almost none. I called my doctor and they were not concerned enough about it to send me to the ER. They just want me to monitor the bleeding throughout the night and go in for an appointment tomorrow. My appointment is not until after work tomorrow afternoon. Has anyone had a similar the thing happened to you in early pregnancy? Is this normal or could this be the start of an early miscarriage?