It was a lot of things that were upsetting her. The lack of not having Clark was probably the biggest part, but it also had to deal with the fact that her hospital was destroyed and she hadn't been able to stop it. That she had to start all over for who knew how many times. And the fact that no one seemed to really appreciate the things she did for the hospital sat on her shoulders.
Oddly enough she missed the island, where there was only a handful of doctors, and they had to do just about everything themselves. The hospital was run by all of them, not just her. She had given up on trying to do anymore paperwork for the evening and put everything away when she heard Mia at her door.
"Hi.. come in.." she waved her daughter in and smiled slightly. "You're not bothering me. If I have to sign one more thing I'll go cross eyed. I'd love to go out."