FIXED! After time and time of tinkering and messing about with no results, I got the problem fixed by doing something so simple that it makes me feel so stupid that I didn't think of it earlier.
So, if you have the same problem as I had, just use the command "unlockall" in the console to unlock the stuff you had lost. Now, I believe the problem of this has something to do with the COD Points as I believe it goes above the allowed amount since having the max amount of it gets you kicked off servers like it did for me. Now, once you've used the "unlockall" console command, go to your Create-a-Class or Killstreaks and spend some of your points to go below the max amount. Once you've done it and you no longer have the max amount, the problem seems to have gone away! I can now join servers and play the game unlike before where I got kicked instantly after picking a class. Spending points also saves your profile so you no longer have to use the console command once you've spent some points and the game goes back to normal. Hopefully the devs see this so they can think of a workaround to this issue since this seems to have been persistent ever since the beginning.
