Change your password (as you have already done) to something more secure.
Change your secret questions! Sometimes people will set their own secret questions (or use the same ones you had with their own answers) so they can get back in later.
Disable IMAP and POP access if you don't use them (account settings).
Consider enabling 2 factor authentication, which will send an SMS number to your phone with a secret code that you must use to log in (in addition to your password).
Consider securing any service which you used that email account to sign up for. Prioritize banks and anything with money. An attacker could have used the info in your email for these accounts to do all manner of stuff and deleted the evidence. Better safe than sorry.
As stated above change your password make it a difficult password 8+ characters. Disable system restore (any virus you may have can hide in restore partitions. Clear all internet cashes and cookies. Delete all temporary files. Download malwarebytes on your computer and run a full scan as well as a scan with your normal antivirus scanner to make sure you have no key loggers. Check that all plugins on your computer are up to date visit this website for EACH browser you use https://www.mozilla.com/en-US/plugincheck/ Make sure your OS has all security updates. If you have a virus/keylogger once it is 100% removed change all your passwords again. Once your computer is 100% clean re enable system restore
Thanks for the advice guys. Just wanted to see what you all thought.
Now this may shock you, about a month ago on my last cell phone bill that there where 32 international text messages made to the same location that logged into my gmail account. I think the two a linked together because I have my gmail account linked to my blackberry. I have contacted t-mobile about this and they say they are looking into it. I have changed all password for anything related to my email account, re-installed windows on my desktop and also re-installed blackberry on my phone.
Sent via my Blackberry