Pregnant. Positive Pregnancy Test. Ultrasound, Heavy Bleeding, Clots, Negative Pregnancy Test. Miscarriage?

i used a pregnancy test strip, it showed positive. i went to the doctor then check again using pregnancy strip, was positive. that day, i went for ultrasound as i told to my doctor i am having light bleeding . ultrasound showed i am 5 wks, but that night i had a heavy bleeding and the next day too, with clots and something like a small intestine that went out with the clots. after 3 days, i used pregnancy test stip and it was negative. i will have a next ultrasound in 2 weeks. could i been miscarriage?