And, since it seems to be affecting your Facebook account, I'd change the password on that too.
A short lesson in passwording:
NEVER use the same password for more than one account, unless it's an account that you don't care about losing (like a throw-away email account).
Never use easy-to-remember passwords - at least 10 characters long, 20 is better. They should be a random mix of upper and lower case letters, numbers and whatever punctuation marks the particular site allows. An app like
Keepass2Android Password Safe makes it easy to keep track of them on your phone, and there are versions for Windows, Mac and Linux. Keeping the data file on a cloud account means that all your devices use the same file, so they're always in sync - change a password on an account in your PC and your phone uses the same password the next time you run it. You need just one difficult-for-anyone-but-you to-remember password for the app - once you're in the apps, all the other passwords can be copied and pasted. (The Android version autogenerates up to 16 character passwords, the PC version can generate an unlimited-length password [I've checked it out to 200 characters, but there's no need for any more than 20]. Even 16 random characters is a very strong password.)
NEVER give a password to anyone. If you sell a phone and forget to remove the Google account, you'll have to give the new owner the password, so he can remove it. Change it to something trivial, like "12345" until he removes it from the phone, then change it back.
And again, never use the same password for more than one account. People
do manage to break into all sorts of very secure sites and steal user files (which sometimes are stupidly even saved as-is, but even an MD5 hash, which is a common way of encrypting things,
can be broken) - and then he has your password. Let it be the password for only that site. (Some people actually use the same very obvious password for everything.)
NEVER use things like your name, your birthdate, your child's name or birthdate, your dog's name, etc., etc. as your password. Someone who's known you all your life shouldn't be able to guess any of them that you use.