Well, first off, let's not "write the script" just yet. You have your appointment for an endoscopy, and hopefully that will offer a bit more info than what you have at the moment. Secondly, don't "hope" that you have GERD!! Anyone on this message board who has been diagnosed with this condition will tell you, in one way or another, how it has ruined their lives. The fortunate ones are those who can manage it, and live the second phase of their lives in a continued, rewarding manner. But the rest of their lives will never be the same, no matter how they manage it -- either with diet and behavior modifications, medication, or surgery...or all three. I was a professional singer, myself, until the symptoms robbed me of my voice. Because I have LPR, even the TIF wasn't sufficient to keep all the reflux from my throat, and I am still struggling.
I know just exactly how you feel about your level of fitness, and how it is a product of your discipline. And the fact that it's a part of your weekly routine, and you do it just the same on the days you want to be at the gym, and even those days you don't. I've been there. Many years ago, I "lived" for fitness, and, to be frank, my life was pretty shallow, full of angst and dreams. I worked, ate, and slept, and spent my free time at the various gyms I belonged to -- either lifting or taking aerobics classes. There was nothing else. Sure, I had pride in how I looked and felt, but that was it. I'm not saying that my situation was similar to yours, just sharing where I was at.
I'm also not claiming that I've reached some sort of metaphysical nirvana, either. As a matter of fact, my life now is nowhere near what I would call balanced. I spend an inordinate amount of time fretting about one thing or another having to do with this condition, doctors' appointments, how I am to proceed, etc. I am intolerant of PPIs, so managing this is especially difficult for me.
You mention "combat sports" -- and I'm not sure what that means, exactly. You're really going to have to wait until you have more information to set a path for the rest of your life. One question you'll have to become accustomed to asking yourself, in many aspects of your life, is, "What is this for?" Meaning, "Why do I do this?" or, "What do I get out of it?" In the case of "combat sports", for example, do you do it just because you have a lot of pent-up energy that you need to burn off in a competitive manner? If that's the case, then maybe doing an Iron Man will give you the same pay-off. That sort of thing...
But if you find yourself prone to anxiety, maybe that in itself is a message to you that you need to take a look at some things that you're involved in, that maybe aren't providing you what you think you want out of it. IF you find yourself diagnosed with some upper GI condition, you can still be active, so try to put your mind at ease about that. You may have to adjust some things, and cultivate different goals, but that's not necessarily a bad thing.
Quite often, I get going on my own "pity party" about how awful my life is now, and the fact that hope is a fleeting will-o-the-wisp that I can't seem to grasp when I need it. But all I have to do is remind myself, right here on this message board, how much WORSE things could be for me. There are folks out there who have much worse struggles. My achilles heel is gratitude, and I fully admit I have to learn how to appreciate the things I have, better than I do.
Hope some of this helps. Again, you're on the right track by seeking medical attention, and try to take one day at a time...breathe...listen to music...spend time with friends...etc. When you need to "step up to the plate" when you get the results from your endoscopy, you'll be ready. But try not to worry about the unknown before it arrives! And, remember too, if you get overwhelmed by medical stuff from your doctor that you don't understand, or want to bounce things off of us, know that there is a wealth of experience available to you here!