I don't know why I allow my HA to control me. I think it's because it's a real legit possibility I could have something wrong with me. No medication or therapist can promise me i won't end up with something I fear there for I think I am truly non fixable. I KNEW this would happen. I knew if my colonoscopy came back clear I would be right back to obsessing over other possible illness. I have a symptom and that's heartburn so something as to be causing that? And I'm scared.
I agree with wegnis that you don't need to worry about offending people—trust me, I've done my fair share. If it helps you, then it helps you. But I think it's important to be aware of what is actually helpful and what isn't. Clearly, googling isn't helpful. I would wager to guess that that is the #1 thing that's keeping you in a cycle of ever-worsening anxiety.
I don't know exactly how old you are, but in actuality, the most legitimate cause for your symptoms at this point is anxiety, and not some form of cancer. You're right that therapy and meds can't promise that there isn't anything wrong, but NOTHING in life guarantees that. What they can do, that a medical test cannot, is to help you learn how to COPE with that kind of uncertainty. Anxiety feeds off uncertainty, so the worse it gets, the more extreme things we're tempted to do to ensure that certainty, but life's just not that way.
That you "knew" this was going to happen actually does highlight the fact that you understand how HA works. I think what you're not grasping is that in order to get over it, you're going to have to change your behaviors BEFORE you can expect a change in attitude. That means RESISTING the urge to run to the doctor, to run to google, to run toward reassurance. I know I've said this to you before, but there's a reason for it and that's because it's true. I'll keep telling you this in the hopes that maybe someday it'll sink in. At the end of the day though, you're the one piloting your own ship, and you're the one who needs to make the decisions.
When I struggled with HA, it was awful but even its awfulness was better than the stuff in my life I was trying to avoid dealing with. Even though I hated what I was doing (the googling, etc) I still kept myself up at night trolling the Internet for health info and getting scared. My therapist said, rather matter of factly, "well, it's giving you something you need," which I wager to bet is what's happening to you. So really, despite all the advice (good or bad) that people on here are going to give you, ultimately you're going to stop the cycle you're in when you're ready; when perpetuating the fear about your health stops giving you whatever you're getting from it. But in the meantime, that's no reason to delay taking your previously-prescribed medication and seeking professional treatment. If you still haven't told anyone in your everyday life about your struggle, it's time to do that as well.