Huge painful knot on head. right side behind ear. should i be worried? could i jave slept on it wrong? please help! im panicking

Cyst or Lymph node: This is a common area to form small sebaceous cysts. They are formed from the oil/ hair folliclles in the skin. They often do not go away. Sometimes they can get infected and get larger or painful. It could also be a lymph node aggravated by a a scalp or ear lobe infection/ inflammation. See your doctor or an otolaryngologist for evaluation and treatment. They are often removed or excised.