Check your posture!
70% of headaches come from the neck. Making sure your neck is well aligned is one of the most important things you can do to get rid of or prevent headaches.
Stand up and have someone take a photo of you from the side. Then draw a line from your ankle directly upwards. The line should pass directly through the middle of your shoulder and also through the middle of your ear.
If your ear is forwards of the line and your shoulder then you’re adding extra weight to your neck which can really start to cause problems including headaches.
To resolve this issue it really is worth finding someone who is trained in assessing and correcting posture.
Till then you need to begin lifting your chest up and your chin up so that your head comes back in line with your shoulders. This might feel odd initially but over time it will become more natural.