As far as I know, the battery calibration thing is a myth especially with the batteries currently made today. If I'm wrong I would like to see some articles/ tests that prove otherwise.
As for the battery, I would recommend going to Apple and get the unit exchanged. Not to jinx you or anything, but make sure you keep that phone super secured. Apple might fight back if there are any dents/cosmetic damages on the unit.
Good Luck.