I just went to Citi Bank's website (which gives free FICO scores from Equifax for users of some credit cards) and I realized that the score I saw there was a whopping ~50 points higher than the number I saw on Mint.com, despite the fact that they both claim to have received the number from Equifax.
The only difference is the fact that Mint checked my score at the end of February 2015, whereas Citi checked it at the end of January 2015.
However, nothing unusual has happened to my credit history in between these two. I can confirm on Mint's credit report that nothing seems wrong, so I'm quite confused:
What can cause such a discrepancy?
Whom should I contact to understand what is going on -- Mint, Citi, Equifax, or other?
How should I contact them -- file a dispute, call them, or go somewhere in person?
Note that I don't feel I'm "disputing" anything, since I don't know if there is any cause for a dispute, and hence I'm not sure it makes sense to open a dispute with Equifax. I just want to know what is going on and why two third-party agencies claim to have received such wildly different numbers from the same agencies in the span of 1 month.