Ugh so sad/scared

So after waiting what seemed like forever to find out what we are having ( a little girl) during my anatomy scan the Doctor noticed a spot on my babies brain. He said it typically found in babies with trisomy 13. He said that everything else looked perfect and healthy. He also said it's extremely common and he sees it a lot and it typically goes away. He recommended further test and to come back and see him in 4 weeks. Have anyone else had this happen. Did it go away? He assured me not to loose any sleep over it and it should clear up but I still can't stop thinking about it.