What actually goes on in your brain when you have a headache?!

What actually goes on in your brain when you have a headache?

There are a lot of different things that can cause a headache. Migraine headaches are caused by dilation (opening up, or swelling) of the blood vessels in your head putting pressure on the nerves and brain. Stress headaches are caused by a tightening of the muscles in the neck and shoulders. Sinus headaches are caused by swelling and inflammation of the sinus cavities in your head. Allergies can also cause headaches as your body reacts to the allergens. Hormones, lack of sleep, caffeine, and lots of other things can cause headaches, and some of these are caused by chemical imbalances of substances like serotonin or something that is irritating or putting pressure on the trigeminal nerve. And of course, there are always the most dreadful--a brain tumor or concussion or closed head injury putting pressure on the brain.