My iMessage quite working suddenly, refused to work on phone, computer, iPad - help please.

Two days ago my iMessage just stopped working in the middle of the day. I've logged out of my Apple ID multiple times - I've changed my password - I've updated to iOS10, I've done everything I can think of - but it refuses to work. Any ideas on how to fix this? I'm using a iPhone 6s. Neither my iPhone nor my macbook pro nor my ipad will send an iMessage - and prior to this, they all did.