What Causes Pink Vaginal Discharge During Pregnancy?

I went for a pt test some days ago using blood they said am pregnant but wen I had seen pinkish discharge when the discharges continued I had an ultra sound and they said they cant see a sac in my uterus and I had an infection in my urine.yesterday the discharges didnt stop when I noticed some blood when I wiped.and I had another ultra sound the doctor found out that my uterus is thick,and he said its too early to make a judge ment .This morning the diacharge is rea blood and having pains. What does it mean?