The voice in your head

You were once skating and a man bumped into you, causing you to fall and get hurt. You were taken to the hospital, and when you woke up, you heard a man's voice, who didn't know where it was, and who didn't remember anything about it. As you, surprised, began searching for the source of the voice, the man spoke in your head:

"Oh, everything's turned upside down... it's all right now..." you even looked under the bed, and when you screamed, the man asked in shock:

"Who's there?"

And so you met... it turns out the man somehow got into your mind, but no one believed you, and to avoid being sent to a mental hospital, you pretended everything was fine. So, you've been living with the man in your head for weeks now. Then, another morning, you get out of bed and hear a man's voice:

"Good morning, how did you sleep?"