its literally the brain being constricted. The body puts too much water around the brain (forgetting the reason why at the moment) causing the giant pressure and pain of a migraine. They also last longer than a half hour. Most of the time they come with sensitivity to lights and sound, you generally end up in a dark room with no noises and an ice pack on your head until the meds kick in. If you look at a light, or hear a loud noise its like a pulse inside your head that can dang near knock you on your knees. Sometimes they come with nausea and in worst cases people actually vomit.
Feel free to message me any questions, I'll try to help the best I can!
Rummy- Mini Rex Rabbit
Diz jr- Betta
Yoshi- Crested Gecko