Blood clot in my uterus

Started having spotting two/three weeks ago. Last Wednesday had a ultra sound the dr found a blood clot in my uterus, he said this is what's causing the bleeding and it will take care of itself and told me to not worry about it. Also saw the little ones heartbeat! And confirmed I was 7 w 1d. Then Friday I went to the bathroom and wiped and there was the blood I've been seeing and then a few blood clots the size of a quarter. Then a few hours later I started having uncomfortable cramping with the bleeding. The cramping lasted for maybe a hour and then I had light spotting the next day and now nothing. I have a ultra sound today but not sure if I should expect the worst. Anyone had the same experiance?