20 week scan couldn’t see back of the brain?

Had my 20 week ultra sound today and the woman couldn’t see the cerebellum at the back of the brain another lady come in to try and she couldn’t either. Iv been referred to a specialist tomorrow but they wouldn’t tell me anything! Everything else was normal spine heart ect but she stopped the ultra sound and took us to a room and said she hadn’t seen this before where the spine isn’t effected and couldn’t tell me anything else so I have no clue what to expect tomorrow! Has anyone else had similar happen? Desperately looking for some positive out comes

Iv had a hard pregnancy so far with getting high risk for downs but I had a harmony test and it come back low risk 1 in 100,000

Then I got diagnosed with hyperemesis gravidarum at 13 weeks and was hospitalised a few times with dehydration from not keeping anything down ☹️