It could be a lot of things other than reflux. Do you see a chiropractor? It could be what's called a hiatal hernia. Typically caused by stress, this is when the stomach gets wedged up under the diaphragm. It can cause nausea, reflux like symptoms, and even what feels like heart palpitations. A chiropractor can do a simple adjustment to release the ribs and the diaphragm.
It could be an allergy or food sensitivity. The major culprits are usually gluten or dairy products.
He could have H pylori helicobactor--the bacteria that causes ulcers. Or some other virus or bacteria that he just hasn't fought off.
He could have a yeast problem (if he's ever had anti-biotics this is likely). Give him some full spectrum pro-biotics.
Herbs that ease the stomach and help digestion include ginger, peppermint, catnip, fennel, and papaya. Also taking food enzymes with his meals could help.
My youngest has had all sorts of stomach problems, so I can speak to all of these things from experience. If you need more assistance, or have further questions about what I wrote, feel free to contact me. If I knew a little more about his symptoms I might be able to narrow these possibilities down for you. I've treated him all with alternative remedies with great success.
Good luck!
J.