Justin Bieber's Public Outburst Might Be Because of Love Life, Dr. Drew Says

Justin Bieber's outbursts aren't just random -- Dr. Drew tells us he doesn't think it's fame or stress ... but drama at home that's lighting the fuse.

We caught up with Dr. Drew when he was leaving Heather McDonald's 'Juicy Scoop' celebration on Wednesday ... and he didn’t hold back -- talking about JB's possible substance use, how Justin's previously discussed dealing with depression, and even potential romantic troubles. In his words, the Biebs looks deeply unhappy and seriously needs help.

Naturally, all eyes are on Justin's wife Hailey Bieber -- and for good reason. Earlier this week, Justin insinuated she was giving him the silent treatment … plus, Hailey was recently spotted without her wedding ring.

Watch the clip -- Drew goes deep, saying the couple's infant son could seriously complicate things if there's trouble in paradise, 'cause the stakes are way higher now that they're parents.

While Dr. Drew refers to Justin's mom as a previous source of support, he points to other BTS drama that could be fueling his public meltdowns -- it’s not just relationship woes, it’s a whole storm brewing.