pain in back right of head

Ok, so before I get to my issue, let me give you a little insight on myself so that it may give some reason to my problem. I am a single 18 y/o living in Virginia Beach, VA. I am attending a local community college, aspiring to join the Radiology Program. I work 5 days a week, about 4 or 5 hours a day as a lab courier at a local Hospital, just driving around from doctors office to doctors office...moderatley low stress. Im a moderate to heavy smoker, averaging about 15 cigarettes a day. I AM a pessimistic hypochondriac...so in other words...if I feel a chronic pain in my leg, its only natural for my mind to automatically jump to "Oh, I have a DVT" (blood clot) Yea, I know you're probably thinking "Oh yea, good idea, you're a hypochondriac so go into the medical field and learn about ALLLL the things that can go wrong with your body."
Ok, so here's my problem. Last Wed. I was at my friend's dorm room, I was sitting on her bed and I got a pain in the back-right portion of my head...it lasted for a minute or two and then went away. I went home about 2 hours later, not having any problems, and once I got home, the pain came back. It would come and go and it was very annoying. I went to bed, and I woke up feeling fine. I felt fine all day, but the pain came back that evening at work...around 6pm. Every day since then, the pain has come back, but it's very strange. It's usually centralized to that back-right part of my head, the pain is very dull and may not even be classified as pain...more like intense pressure. Some times I feel it in other parts of my head (back-left, right side above my temple, etc.) but its mostly in that back-right portion of my head. It's been almost a week now, and of course, my first reaction was "!**@!, I have a brain tumor" I am afraid to go see a doctor because I dont want him to tell me something I dont want to know. Can someone shed some light on this situation?