Your headaches may be a sign for something more serious. If your headaches include vomiting or nausea, it could be a sign of a brain tumor. A quick onset of pain may be signs of an aneurysm. Muscle weakness or limb numbness can be stroke indicators. Stiff neck or fever could be a sign of meningitis. Though many headaches aren't anything serious, it is important to pay attention to your body and immediately see your doctor if you think it may be something more serious.