A photog got this shot Thursday in Bev Hills, at the medical office where Justin gets his IV vitamin drips.
He clearly got emotional as he left ... clinging to his bodyguard and looking pretty sad.
JB said a few days ago ... he was leaving his wife, Hailey, behind in L.A. to embark on a spiritual retreat to clear his mind. What's unclear ... is there any connection to the release of Selena Gomez's song, "Lose You to Love Me." People have been doing mashups with Selena's song and Justin's, "I'm Sorry."
Justin's battled depression in recent years, but it seemed like he was on the upswing. Hopefully, this was just a moment in time.