Oral bactreria are the cause of the majority of bad breath/ Halitosis cases.
Consider doing TWICE daily, upon rising and before bedtime,
Oil Pulling with coconut oil to help you excrete billions of bacteria
and toxins from your oral cavity.
The acid reflux theory could have some merit, nonetheless, it should be treated regardless, as it may have other consequences, but keep in mind that low gastric acid is more prevalent in acid reflux than excessive gastric acid.
Doctors are too fast to prescribe acid blockers & PPIs without actually checking gastric acid levels... a dangerous path to take.
Please note that my comments are not intended to replace medical advice..
best wishes,
Niko