No one knows when bitcoin going to cross $20k, we can't predict. For now its in $11000+, hopefully it will continue to rise until it reaches $20k. But i think not this month.
I don't know why bitcoin dropped from 19K USD to 11K USD, it is a very unsightly for all of those people who waited for bitcoin's price to hit 20K USD but suddenly it didn't, it is very disappointing to be honest. Right now, we are hoping for bitcoin's price to show us some signs of its resistance so getting back to its track is possible again to happen this month or next month.
There is no reason to panic though, just hold your bitcoins if you don't need fiat and wait for its comeback to have huge profits.