I have been getting headaches for the past four days because of oversleeping. i never had a headache because of oversleeping before. what is happening to my body?

You may be dehydrated. Drink enough water, dally, so that your urine is mostly colorless. Go for a long walk in fresh air. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV and Covid vaccines. Wish you good health!