I've had the same symptoms you describe for 2 years and I'm 26yo male.
First you have to let go of your worries of having cancer; the fact that your friend had cancer and with similar symptoms does not tell you have cancer; it will only stress you further with that constant worry. Although, if you need hardproof I would get tested (not sure of the actual tests) just to give you piece of mind.
I've been battling post nasal drip, oral thrush, fatigue, panic attacks for a while now, and is due candida and parasites. These typically go undetected by allopathic medicine so I could be that you need to take a different perspective on your symptoms; I would do some research here at curezone to try to have a rough diagnosis; I can think of several causes for your symptoms so it requires deeper research (and testing) to determine the actual disease.