You have to take the PPIs the way they work, not just when you feel reflux or pain. You have to take them on an empty stomach half an hour to an hour before eating, and then you MUST eat! The little acid pumps in the stomach wall have to be turned off while the medicine is metabolized and gets to them, and THEN you must eat to turn them on so the medicine can turn them off. Sounds stupid, but that's the way they work. The 20 mg dose won't do diddly, which is why your doc told you to take 2.
I never got relief from Prilosec, but got good relief from a couple of others. If one doesn"t help, try another. Look through your insurance's formulary and see if there's one they will pay for.
I had no trouble switching from one PPI to another with no break in between. They're all similar meds.
As for diet - Is there any possibility of certain foods triggering reflux? It's pretty common for people to have specific food or chemical triggers. My trigger is sulfites, found in specific foods. Keep a "food journal" (see pages in the archives - the search box at the top of the page). My allergist got me doing this and it was a godsend!
I kept my stomach non-acid, avoided my trigger foods and only had to be concerned with fluids coming up if I was not elevated on two pillows at night. Beats surgery! I eventually had to have surgery (Nissen) after an accident that shoved my stomach into my chest. But I still have to avoid my trigger foods.
My allergist lumps everything (sensitivities) as allergies. I didn't have the delicious sounding grilled chicken vegetable salad at restaurant tonight because it had sunflower seeds, which would have sent me to the hospital in tachycardia. I learned years ago to avoid like the plague my favorite barbecued pork ribs (pork, brown sugar, vinegar, loaded with sulfites. Oh yum.). I'd get tachy in the parking lot on the way out, every time.
The "usual"foods to avoid have nothing to do with a lot of us. Bland does not mean it's good for you. I can't eat corn syrup, corn starch, garlic, boxed or canned potatoes .... I'm fine with coffee, tomatoes and many other non-bland foods.
Put a notebook on your kitchen counter and give it a try. Ignore fad diets, the latest cures, etc.