Failed to verify username after name change

I saw that you were able to change usernames. So I went to change it and it said it had done it successfully. But then when I try to log into a server, I am greeted with a 'Failed to verify username' message. I have tried to update my client, relog, relaunch minecraft. And even go back and try to revert my name change (but unfortunately you cant, as you have to wait 30 days.) If you would like anymore info, please let me know and give me directions, as this kind of thing isnt my strongest skill.