Help?

Brooklynn • 23, married, mom to 2 wonderful boys, Mason and Tristan, and a 3rd boy is due July 9th, 2020.
Okay ladies, my best friend who has a 6 month old baby girl is 19 days late and has gotten negative tests repeatedly (including one from last night). Has anyone gone through something like this and what was the outcome? She feels nauseous and tired. Hasn't cramped ANY, and she has never been this lAte before. Any insight would be greatly appreciated. 
Note*****  I've encouraged her to go to the dr and she's going to make an appointment as soon as she can.