Baby is at risk for Down Syndrome

Migdalia
I am 17 weeks and just had my Quad Screen Test. Got a call from my doctor telling me that it came back positive meaning my baby is now at higher risk for Down Syndrome. I am totally devastated, feeling sad and guilty... 
I am going for my 2nd ultrasound, so nervous not sure what to expect. Any personal experience that someone can share? I need some type of comfort.