My account balances have changed

Title, also the denomination changed from DOT to BDOT. Can anyone explain what has happened? Also did I just get hacked?

Update.

It appears there may be some sort of runtime error/bug that can make your wallet balance look like there is more than there is, when the polkadot.js.org extension updates.

This is the most likely culprit atm, if anyone here can verify that would be great.

Thanks.