Hoping baby will be okay

Hi I’m 15 weeks pregnant and I was just wondering if any of you mamas have experience something similar to my situation and I just want to know why it would happen and if it means something. This is my first baby and I am so excited to one day meet him/her and as I know many of you just would want your baby to be ok. So today when I went to pee at 3 am I noticed that I was bleeding a little and when I looked in the toilet I saw a blood clot similar to when you get your period only it was just that and not even blood in the water. So we headed to the hospital and as you can imagine I was scared and prayed that my baby was okay. Once in the hospital they checked my vitals and a urine test. Then they did an ultrasound to check on the baby and baby was okay and moving sucking his/her little thumb so that was a huge weight off my chest. And the doctor explained that the baby was okay and that my urine showed no infections but it looked pink that maybe it could be bacteria buildup in my uterus but nothing alarming. They sent my urine test to the lab and Its going to take 3 days till they get the results back to let me know. Has any of you experienced this before, what is it and what causes it?

Thank you