Mine did the same thing a few weeks ago.  This is how I fixed mine.... not too sure if it is the actual solution, but it worked for me.  First, I went to Facebook on a computer and logged into my account.  I located the profile picture that was incorrectly showing up on my phone and deleted it from my Facebook page.  Then, I used my 920 to choose my new profile picture as I normally would.  This fixed the problem, and the incorrect picture did not show up any more.  Hope it works for you too.