Since I don't have a 5100 I have a 3000 instead (bought 2 days before the 3100 hit the market typical of my dumb luck).
But in The WB settings on the the 3000 there are three Florescent settings. Warm White , Cool White and Daylight. Then the are the settings for Out Doors, Flash night time and so on.
If the Pictures are pinkish set for Cool white or daylight instead. if the have a Blueish cast then set for Warm White or Daylight. Cool white add a little extra Blue, Warm White a little extra Pink. And Daylight mimics sunlight.