Can Coughing Lead To Miscarriage?

Hello there, i had my last period on the 19th of march, so technically i'm 6weeks+4days pregnant. I developed a nasty cold and started coughing really badly and went on to have abdominal cramps about 4days ago and also started bleeding. The bleeding went from small brown bleeding to fresh looking blood and the flow is like a period. I am still bleeding but the cramp has subsided. I had a scan yesterday but no sac or baby was found. My HCG level is 445. Pls what is happening to me?