Recently, I have a sneaking suspicion that I have brain cancer
Why do you think you might have brain cancer?
I have physical symptoms. I have been experiencing headaches recently and saw that my roommate has been having the same symptoms
Headaches can have a lot of causes so you probably shouldn't try to diagnose yourself. If your roommate has the same problem it could be something in your room like mold or mildew. You should probably see a doctor to get checked out anyway if you're worried.
Explaining to doctors that I'm worried that I have cancer makes me anxious. I don't want to bother giving out that much personal information either. It's better for me to stay in denial and pretend like nothing is wrong with me.
But don't you want to have some closure and peace of mind that it's nothing serious? Diagnosing yourself and your roommate can be quite dangerous so I believe it's best to leave it to professionals. You really need to see the doctor so you can be healthy again quickly.