I was always fit also, I just overdid it with coffee. I used to work in logistics so I got used to drinking a lot of coffee, like 3-4 larger cups per day. Later when I had to buy coffee, I bought Americanos twice daily with extra shots of espresso. I treated it like regular heartburn but what I didn't know is that caffeine makes your lower esophageal sphincter relax, and allows travel of acid upward which causes the heartburn. I refused to quit, and it never stopped - when I tried to get off Prilosec it felt like hot coals in my esophagus, agony. But after I quit caffeine for good I am now able to get by on a h2 blocker whenever I want to eat some spicy or really greasy food. It's been over a month for me now. I'm also going to get tested for https://www.webmd.com/digestive-disorders/h-pylori-helicobacter-pylori#1 because it's a possibility that it's a contributing factor.

I wish I had done this much earlier in life, I would probably be able to not take anything but I really think I did some damage to my stomach over time by refusing to quit caffeine and just patching the underlying behavioral issues with pills (Prilosec).

Edit: Reason I went into so much detail is because I want you to understand the nuances of my situation, and that it may not exactly apply to you - or at all depending on a myriad of variables. But I think it's something worth trying, - quitting caffeine if you have reflux symptoms.

For acid reflux, or GERD, stop drinking caffeine and never eat a big meal a go right to sleep after. That's what gave me acid reflux. I got over it not with meds, I mean they helped but couldn't get rid of it for good, but rather by cutting out caffeine and eating a lot of oak meal a cream of wheat.

I use to eat a lot before bed too, not anymore, it's horrible for your stomach apparently.