Terribly scared😭

So yesterday I went in for my 20 week scan super excited to find out what we were going to have. She began the ultrasound and quickly told us, It's a boy! We were beyond happy.. When she was done she left the room only to come back to let us know there's something concerning... I freaked out. She said it looks like the baby has fluid on one side of the brain.. I'm devastated. Don't even know what this means.. Waiting to see a specialist tomorrow.. Anyone else been through something like this?