Amnesiac
He felt his feature change in a single painful burst. Then jolted forward and was greeted by the face of a young woman. He looked rather surprised at her. She stumbled back away from him. He saw her face sadden in an instant. Her face was the first face that his new face had seen and he had made it sad for some reason. He cautiously made his way over to her, testing out his new height for a moment before crouching down to her to get a closer look. Who was she? He searched his brain for some indication as to who this young woman who was with him, but no name came to him.
Then there was a sharp pain in his side, he clutched it as tissue joined together to form something new, something that was there before. There was a name, he knew the name of them, and what were they.
"KIDNEYS!"
"I've got new kidneys" he heard a voice say, his voice. His new voice.
In an instant, he could see a glimpse of what they looked like within him. Oh no.
"I don't like the colour" he said rather disappointed.
"Of your kidneys?" The girl replied dumbfounded.
All of a sudden they both found themselves flung about as the TARDIS finally reacted to him.
"What's happening?" she asked rather panicked.
"We're probably crashing! Oh!" he found himself saying as he was flung forwards briefly in the direction of the doors before he managed to regain some composure.
"Into what?!" she said rather afraid.
"Stay calm." he told her trying to reassure her as he ran quickly to push some buttons, trying to remember something about flying the TARDIS, but nothing came to mind. He couldn't remember anything.
"Just one question." he said to her.
She slightly leaned forward slightly.
"Do you happen to know how to fly this thing?"
He looked over at the girl as she just recoiled back slightly fearfully.