Why do my eyelashes keep falling out!?!?

Basically, today i got into an argument with my mum and it made me cry, and after i had made up with her i realised that some of my eyelashes had gone. It's hard to explain, basically i cry and then wipe the tear away either taking the eyelash with it or scraping of all of the skin leaving my bottom lashes bald. I don't wipe it with pressure and this only ever happens when i cry for a long time. It has happened before and my eyelashes grew back. I can't find any answers on google or anything, it's really strange?