I’m so sorry you’re dealing with the pain and disruption to your life that comes with severe heartburn. I’ve had nausea and GERD as well. What helped with those issues for me is a combination of figuring out triggers, taking Famotidine (I saw you already take Pepcid), Zofran, and time. Figuring out my food and beverage triggers was frustrating because it seemed like everything made me nauseas and have heartburn. So I initially gave up coffee (all caffeinated beverages), alcohol, gluten, dairy, red meat, nuts, tomatoes, onions, garlic. For a while I ate only oatmeal, unseasoned chicken breast, celery, cucumbers, applesauce and GF pretzels. I also took probiotics and drank a shot or two of lactose-free Kefir each day. After several weeks I slowly began to test other foods to see if I could tolerate them or if they’d trigger the nausea/heartburn. After almost 5 months I can now eat red meat again. I can eat most berries and a few raw vegetables. Spicy foods, onion & garlic, caffeine, sweets, alcohol, gluten and dairy, are all still triggers for me. And I still take Famotidine 2x daily as well as probiotics and Kefir. But I’m off Zofran and only occasionally deal with nausea or stomach pain or heartburn. Since inflammation seems to be the cause of all Covid related issues, it just depends on where that inflammation settles and clearly mine was in the gut, I’ve tried to learn ways to reduce inflammation in the body. I also practice slow breathing and yoga and avoid stress when possible. I hope you can find what works for you so you can get relief. I know how disruptive to life heartburn can be and how painful it can get. It will eventually get better with time, but see if any of the things I mentioned help. Or if you find something else that works, please post & share.