Im so worried 😞😞😞

Perla
So I'm 25 years old and I'm 21 weeks pregnant. I just had a level 2 ultrasound on Monday and got a call today. They said they found a white spot on the baby's heart . The doctor told me not to be alarmed but that it may or may not be a marker for down syndrome. Apparently this is a common thing and sometimes it's nothing. As I go back to the beginning of my pregnancy, i cannot think of anything I might have done wrong. I'm not a drinker and I have never been a smoker. Have any of you guys had the same call? If so how did it go? How's your baby doing? PLEASE ANYONE? btw this is my first child.