Super scared!

By my last menstrual period i should be 8 wks 5 days...but this morning i was experiencing a really bad headache and feeling extremely dizzy. Called my Dr. And he suggested to just sit back a relax for a while that probably it was just my hormones. Around noon the dizziness was getting worst. Decided to go to the Er, they drew blood(all was normal) urine test(showed a little infection uti) and did an ultrasound which the results got me in tears. They said all they could see was a sac and nothing else. So now im super devastated. I dont want anything to happen to my baby. Im suppose to schedule another ultrasound in a week and im super scared for the results.