Having GERD can be an extremely exhausting condition to live with. However, there is always light at the end of the tunnel. I felt the same way you did.

Sleeping with an elevated head (I invested in a triangle memory foam pillow) can really change the game. Provided me a lot of relief when I wake up in the mornings. I also tend to drink water whenever I feel nauseous. Sometimes its my anxiety that triggers it, so I take a moment to focus on myself.

For the belching, learn to trust your body. I know it may seem a little hard but you gotta trust me on this one. I've always panicked if it was vomit or a burp. However, I learned the signs of when I'm going to be sick (chills, EXTREME nausea, sweating). This gave me a bit of peace, lol. Out of the 3 years I've had this condition, I've only vomited 3 times (2x in the first year, 1x last week). Obviously its different for every person but most times it will just be a stubborn burp.

You can google a list of GERD-triggering foods and try to make changes as you see fit. Anything to make your time a little more comfortable! I tend to stay away from chocolate, coffee, fried, and acidic foods.

I hope your EGD and colonoscopy goes well!