Knicks center Mitchell Robinson opened up about his mental health after he and Hawks guard Dyson Daniels  were both ejected for fighting in Game 6 of their first-round playoff series Thursday night. “Knew something was gone happen,” Robinson wrote in a Facebook post after the Knicks’ 140-89 series-clinching win — and the largest win in a playoff game in franchise history. “My mental just not the same I’m just lost in the world at the moment.” Robinson also reshared his pregame post that said, “Trying so hard to be calm.” That comes as new video footage, appearing to be from a fan emerged on social media. Taking to his Instagram Story, Robinson posted a video that showed a cartoon animal singing the message: “Hey, I gotta question cus I really need to know, do you ever get tired of being bitch ass n—a, .p—- ass n—a.” Warning: Graphic Language Things got chippy when OG Anunoby made a pair of free throws to extend the Knicks’ lead to 50 points with 4:39 remaining in the first half.…