Yeah I get massive migraines when I'm stressed, cortisol levels rise through the roof. I don't get stressed usually but when I do its just overwhelming. You've just got to get over what's making you stress, a bit is okay, it means you care. You should make a list of things you want to get completed and drink a LOT of water/ eat fruit because the more healthier you eat the better you feel. Also, don't feel down if you haven't done everything you wanted to, sometimes that happens. Maybe write down things you DID complete so you feel like you're being somewhat productive.