Am I being Hacked?

So Today I logged on to Fantage, Finally ..
It said "Congratulations You've logged in 7 Days in a row! You get 500 stars!"
Then it said My star balance before and after which was the same amount I left it so
I was just looking at the screen like *I Haven't logged in, In at least 4 days. So I'm confused out of my mind Then I x out of the Start screen and my outfit is changed, I knew it was changed cause whenever I'm about to log out I change into the same outfit and I did not change into blonde hair, pink sneakers, and a black feathery board..The top and bottom were the same though. But I didn't have my cat ears and headphones on so I'm looking around in my inventory and everything's the same.. I think. So I also checked my ID phone and everything was normal.. But I really hope that this person doesn't continue to get on my account because It bugs me. even if it's one of my friends.. It bugs me A LOT cause they could spend money, or sell my things or something and I'm not down for that. And I'm definitely not down for them changing my clothes. >:( Ugh. I've had such a tough week.