Hi , I;'m not sure if this is the right thread for the problem that I have.. (I sure hope it is)

Okay here is my problem, yesterday I woke up with a bump that hurts to the touch as if it's a bruise...on the bottom of my head on the left side. Today it's a bit swollen and hurts regardless if I touch it or not.. I can't turn my head because it hurts a lot...I have no idea what it is... can someone please tell me what it might be...or what can I do to help it or should I worry..