Anxiety or brain tumor?????

I have been experiencing many of the same symptoms as everyone else for about 4 years now. I had to have an emergency surgery (on something completely different) when I was a freshman in high school and because of that I think i developed severe hypochondria. For about 6 months after my surgery my mom had to rush me to the emergency room for random aches and pains because I thought that I was dieing if she didnt and had horrible anxiety about getting a disease or dieing at such a young age. When I was a sophomore I convinced myself that I had a brain tumor because i had a headache on one side of my head. I still tend to get this headache but I'm not sure if its a real problem, or if I get it from thinking and worrying about it. I also grind my teeth at night. Its on the right side of my head towards the back, like behind my ear. Its not like sharp pain but more like an ache, and gets worse when i have time to focus on it. When i am busy i tend to not notice it. It sometimes almost feels like when you jerk your neck too fast and you get that tingly pain through your neck and back of your head. I really have no other symptoms at all. I just found out that a friend of a friend who is my age was diagnosed with a brain tumor after just having a bad headache for 3 days. It really freaked me out and now my headaches are worse than ever and I spend all day looking up stuff online that scares me. I am scared to get an MRI or CT scan because I dont want to get bad results. Anyways I am freaking out and so scared that I have a brain tumor. I truely think that it is from my bad anxiety (by the way--i was put on anxiety meds soon after my surgery when my doctor realized how many ER visits I had been making but i went off of it years ago). I would hate to overlook something more serious since I now see that a normal 20 year old like me can get a brain tumor. Anyones comments or advice would be greatly appreciated especially if you have been through this same worry and fear. Thanks so much!