The Doctor was looking at her "Oh? I am sure its nothing, probably just very tired. I am not one to sleep a lot." though the Doctor knew it was more than that, he was trying to keep her from worrying about him. He was always trying to stop people focusing on how he was a lot of the time. Though the Doctor stumbled and leaned on the TARDIS. He closed his eyes.
He felt a little dizzy, he wondered what was doing this to him. That seemed to be the only possibility when he didn't feel good.