Are you on a mobile device especially a tablet? Are you having trouble with newer content (E.g. City of Um or Fort Forinthry)? I am. I got told that the mobile team was working on fixing the phone interface and maybe I should try bypassing wifi by plugging in.
I am assuming your computer specs are above the minimum system requirements since you mentioned you've been playing before and the crashing started out of the blue?
Did you do anything differently that could have triggered the crashing e.g. updating OS or install anything?
Unless you haven't tried these steps yet, I recommend you to restart your computer, reinstall the game client, make sure your graphic drivers are up-to-date and also
clearing your cache
might help as well.
Hope the crashing stops in a way or another, it can be very frustrating to play like that.