Macbook Pro wouldn't let me log in unless I switch user!

I have an early 2011 model (10.9.5) macbook pro 15". Today all of a sudden when I turned on my laptop, I no longer could see my account profile that I always log into. Then had to restart, Command+R and then learned that the profile is not even listed there. I login as root, created a new account using the same account name as the one mysteriously disappeared, selected the "choose the existing /User folder" option and everything went back to normal.

1) Now when I reboot my machine and get to the login screen there will be two boxes, one for my username and one for my password. I put my username and password and it logs in just fine.

2) But when I press ctrl+shift+eject to lock my screen, when I want to log back in it shows me my username (already on there with the user image so I cannot change that) and there is a box for the password. The problem is when I put my password in that box, the box starts shaking which means the password is incorrect. I can no longer login unless I press the "switch user" button at the bottom of the screen and then get those two empty login boxes as explained in step 1 above and type my username and password. That is the only way I can login!

Does anyone have the same problem? Any help would be much appreciated,

Thanks