Special Forces

Collin Gosselin says he's passed multiple psych evaluations with flying colors ... and his mom's the one who needs to get checked out.

We got Kate Gosselin's son in NYC hours after his mom implied he was struggling with mental illness ... and he returned fire.

Collin tells us he's grateful for his dad, Jon Gosselin, who he says has his back following the abuse allegations he leveled at his mom.

And as for Kate ... Collin thinks his mom is due for a psych exam.