front right sided head aches

Okay so for the last week or so I've been having headaches on the right side of my head and its usually in the front. it feels like a pressure under the skin kinda thing and it gets worse when ever i imagine a picture in my head. for example if someone describes a bird to me and i imagine what that bird would look like the headache gets worse. I've also noticed it starts later in the day usually when school ends around 2:30pm it starts and its usually a 6-7 on a 1-10 scale and pain killers dont help. Any ideas of what it could be? i dont think its food related seeing as the head ache usually starts around the same time and i dont eat the same things every day. please help if you can.