I'm sorry to hear you have a derogatory mark that's bringing down your credit score, I understand that it's confusing when you're not sure what something like that could be. Unfortunately there is no way to see what that is in Mint, the free credit score does have limited information. However the score is provided by Equifax, so I would recommend getting your free annual credit report from them (if you haven't already); you can get one from them as well as as the other 2 bureaus for free once a year. More info at https://www.annualcreditreport.com/index.action
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