I hit my head hard on my bed so whenever I lie down, the side of my head throbs. Doctor?

Hi :]

If you have some ice, apply it to your head. The pain SHOULD be gone in the next few hours.

If it gets to the point where the pain is unbearable, definitely go to the doctor.
Even if you're concerned for head trauma/damage, go to the doctor.

you need to buy a bigger bed