I keep having to unlock the same things over and over again for Battlefield 3

I was playing Battlefield 3 and my friend said that he lost his progress and some unlocks when I left the game (he didn't leave early). I laughed at him because at the time, it wasn't happening to me. Now I am really close to leveling up to level 24, but every time I leave at the end of the match, I'm back at being a couple thousand XP away from level 24 and most of my unlocks are gone. I have had to get to 24 for the 4th time now and I have had to unlock the same sight for a gun 3 times.

What could be causing this?

It's a known issue. It is prevalent when using the FAMAS, but others have reported it happening (myself included). DICE says a patch is forthcoming, although it will probably not be included in the June 4 mega-patch.

http://www.computerandvideogames.com/350208/battlefield-3-stat-freeze-glitch-blamed-on-famas/