Kidney Stones and Preterm Labor

I had to make a trip to er Saturday night because of pain in my left side. I had felt off all day, but the pain wasn't really localized untill later that night when it got really bad. I had nausea and vomiting and finally called the doctor. She said to go to the er for an ultrasound of my kidney. When we got there the pain wasn't as bad. They asked me to leave a urine sample and when I did, there was blood in it. I freaked out because I am 15 weeks pregnant and couldn't tell wether it was vaginal or from my urine. Shortly after that it got really bad again. They gave me some pain meds and nausea meds and that helped for a little while. They finally discovered through ultrasound and my symptoms that I have kidney stones and said they really couldn't do anything because I was pregnant. I was told that puts me at an increased risk for premature labor. Is this true? They want me to pass them on my own. Does this all sound accurate?