I’m 22 Weeks Pregnant And I’ve Had 7 Ultrasounds This

I’m 22 weeks pregnant and I’ve had 7 ultrasounds this pregnancy I just had one on Wednesday and the doctor had said my babies nuchal fold was measuring 6.6 mm and could have Down syndrome but that was the only indication. I’m worried sick does this always mean that and why are they only seeing it now my 20 week scsn was perfect according to the tech