My back tooth cracked but only hurts when i'm laying down ?

You need care now: When you lie down the blood pressure in your head increases which can cause throbbing in areas with inflammation or infection. This won't cure itself. Please call for an appointment.

So far: Without proper dental treatment, the pain will get worse and be all the time. Don't wait. See a dentist asap. These types of situation only get worse with time and flare up unexpectedly and often when no dentist is open for emergency treatment.

See the dentist: asap. It hurts due to the increase in blood pressure in your head when lying down.

See DDS: See your dentist immediately. You are on borrowed time before the tooth will be hurting all the time. The dentist will ascertain via a clinical and radiographic examination whether a simple restoration is needed or something more complex.

Only?: Your teeth shouldn't hurt at all. Pain is a red flag telling you there's something wrong. If crown is fractured the tooth may be repairable. If root is fractured it will need to be removed and replaced. Delay increases risk of infection and worsening of the fracture. Please put down the computer, pick up your phone, and call your Dentist. Good luck.

Visit your dentist: The cracked toothe is a sign of a problem that won't go away by itself.