You were most likely hacked. Change your password immediately to something unique to FFXIV, and make sure it's complicated. Do not share it with anyone at all. You'll also want to scan your computer for key loggers and make sure your antivirus is up to date. Someone else definitely got into your account. Also check your email to make sure it's not hacked, you may want to change your password there too. It's possible they hacked your email and were able to get into your account that way.