Usually acid reflux doesn't give stomach aches, so I'm wondering if you have something else but related. Maybe slow digestion. So you can try to take probiotics to aid digestion. Eat almonds. Chew your food thoroughly. Ask the doctor how to treat if it's not reflux.
You shouldn't have any seltzer or soda. Eat and chew very slowly and thoroughly, with your mouth closed. (less air in your stomach, better digestion) Drink water from a cup and not a bottle. Don't drink with your meals. Only drink up to a half hour before and an hour after, to allow your stomach to digest the food. You can chew gum (or just chew) at any time you feel symptoms because the saliva aids digestion.
Stop completely caffeine (in coffee and tea) and chocolate. (these keep the sphincter open)
After eating, try to stand and walk around.
Don't slouch, especially during and after eating, and stretch your chest and shoulders back
If you're not already using it, try Gaviscon at night or after a meal. It minimizes the acid effects
Best of luck