help! threatened miscarriage, low laying sac

I am currently, supposed to be, 6 weeks and 3 days pregnant. Last Friday when I got up to pee I noticed a light pink spot of blood as I wiped. I went to see my doctor which then told me my cervix was closed and sent me to the ER for blood work and an ultrasound. Everything was normal... Saturday night I got really bad cramps, heavy bleeding and had to visit the ER where they told me I had a UTI. As I peed to give them a sample a transparent, deflated balloon like tissue about 4 inches long with clots was laying in the toilet. Monday, at my follow up an ultrasound showed the sac was still in my uterus but seemed to "move lower" from the last ultrasound. The bleeding & cramps have became way less intense. What is going on, I won't be seen for another 2 weeks!