We can think of so many reasons why!

Blac Chyna ran errands around Sherman Oaks in her new Ferrari yesterday, and while she's normally more than happy to have her picture taken, this time she did her best to hide behind her phone. Maybe she's trying to keep herself from talking smack about Rob Kardashian? Or perhaps she just got fresh lip injections? Either that, or all her recent hookups are catching up to her and she has a nasty cold sore.

We asked the former stripper about Rob's alleged recent weight gain, but she opted to keep her trap shut. That's probably best, considering they're still hammering out a custody arrangement over daughter Dream, and anything she does or says can be used against her.

"Rob and Chyna's lawyers are working out the details of their custody situation quietly. Chyna and Rob don't talk to each other at all. Only the lawyers are in communication with each other. They're doing this so they can get along for the sake of Dream. The case will be done and closed quietly," a source dished to Radar.

Let's hope grandma Kris Jenner and some nannies are helping out, because it sounds like the reclusive sock designer isn't in very good shape physically or mentally amid all this drama.

"He's the biggest he's ever been. He's well over 300lbs now – we don't know as the scales don't go up past that – and he's a heart attack waiting to happen. He's been comfort eating big time. His fridge has become his best friend," another source divulged to the site.

"Kris has cut him off as of now and she won't be handing him another dime until he confronts his problems. He's got major anger and addiction issues, brought on by a chronic lack of self-esteem over his looks and his position in the family. He's lost the will to live and if it wasn't for his little girl he'd probably not have made it," the source added.

We wonder what her next move will be? You just know she's scheming!