Please read, scared. TMI

Basically I'm 6 weeks 5 days pregnant. I've had spotting since I convinced. (Brown & very light) I woke up this morning and I had heavy red bleeding (no clots) lasted about an hour. (9am).  I went a wee again at 10am to see if I was still bleeding I wasn't and a long brown stringy clot came out) went to see my doctor he sent me straight to EPU. And the doctor there is sending me back tomorrow for ultrasound. I only had a scan yesterday and saw a healthy baby/heartbeat....  4pm no bleeding since this morning only brown spotting when I wipe..... Am I having a miscarriage..