Possibly a solution!
I can log in now. For some reason changing the password appears to have fixed it; however, I'm not sure why that is, since earlier today I tried changing the password and it was still not letting me log in. The only notable difference now is that, my original password was nine characters long, and the first time I changed it I made it ten characters long; the second time (this time that it worked) I changed it to only six characters long. Now it works

Could it be the length of my password or possibly just changing it again got it to 'kick in', so to speak? Oh well, at least it works now

For anyone (like the original poster) who is experiencing the same problem as I was, try just changing your password a few times, hopefully it'll work for you too.