Well so far your symptoms sound very typical of GERD and IBS and really, it is very common for people to have no GI issues a single day in their life until these pop up. (and the upper stuff could also have functional aspects and that is common as well).If the highly invasive or high radiation tests actually showed anything (Even if they indicated your symptoms cannot be from anything other than what you have already been diagnosed with) would it change anything. You won't treat your anxiety and you've had that all your life, you so far won't treat the GI issues that have been diagnosed, is there anything that would change that situation. Or would you refuse any other medication even if they found something else. Anxiety in a way that makes you refuse any medication given to you by a doctor for anything is actually pretty common. Many anxious people just know (and sometimes obsess) that any side effects must be so much worse than any benefit that they will not take anything no matter how bad the condition or how rare the side effects. I dunno if that is how you operate, but is pretty typical of anyone with anxiety or OCD issues, even if mild enough they don't effect other areas of their life.If you won't take medications and no diagnostic test would change that then there really isn't any point doing a bunch more tests just so you can check them off the list and possibly make you more at risk for cancer later on as CAT scans of the whole body look for everything type (which sounds like what you want) may be more risky than helpful unless there is a darn good reason to do it. And often if test A doesn't give you whatever answer you think you want (and sometimes even if it gives a very good answer) then people will just move on to test B, then test C, then test D, etc. that they will doctor shop until they find someone that cares more about making money from doing the test than any benefit or risk to the patient.Yes, a food log for a couple of weeks can be helpful. But you may want to look at how your food log is kept and how obsessive you are about it. Like a lot of things, some is good, too much may indicate a problem. If after a couple of weeks no pattern is starting to show up a couple of months or a couple of years will not make one show up. Most doctors request you do from a 3 day to a 2 week log, not endlessly.Now some doctors and some patients are not a good match so you may need a different doctor that is a better fit (just like you wouldn't say you could marry all women because some are a better fit than others).IBS and GERD are not that much of a "no one knows enigma" as you think. I mean after all IBS starting up after a GI issue because of damage to the control of the gut is a pretty well established theory with a lot of data to back it up. Now a lot of time doctors don't have the time to really explain (or know how to explain them) but they really aren't things that do not know how to treat or have no idea why anyone has them. They are a lot better understood now than even 5 or 10 years ago.