1. You Feel a Sudden Intense Headache

A headache is something normal, probably stemming from stress, lack of sleep, physical injury, etc. In these cases, the onset of a headache will start from mild and then may or may not increase in intensity. But, if you are feeling fine only to have a sudden, sharp headache hit you out of nowhere, get yourself to a doctor immediately! A headache that builds in a mere matter of seconds could be an indication of a brain aneurysm or a blood vessel bursting.