possible thickening of my babies neck

Chenoa
Had my scan yesterday I was 11 weeks and 4 days the lady that did my scan said to me everything is looking perfect babies heart beat was 166 had all hand fingers feet and toes the brain was developing and Bub was getting enough to eat. The baby was very active and couldn't stay still I left feeling awesome, later in the afternoon get a phone call from my doctor saying I have to go back for another scan my babies neck my possibly be thickening they want to double check it I'm kinda freaking out but my heart is telling me everything is okay.