As I know from my own experiences with food allergies (soon after I eliminated gluten and dairy from my diet, my chronic heratburn/acid reflux problems disappeared), ailments of the digestive system can stem from causes that have nothing to do with those funky leftovers you ate last night. I was researching black mold for other reasons, but my eyes widened a bit when I saw the list of possible symptoms.
According to mold-help.org, "The molds that produce airborne toxins that can cause serious symptoms, such as breathing difficulties, memory and hearing loss, dizziness, flu-like symptoms, and acid reflux. Common ailments from toxigenic mold---including allergies (hypersensitivity after initial toxicity), and excessive bruising---usually can be treated and reduced after people leave their contaminated environment."
If you suspect you may have mold in your house, car, workplace, or anywhere you spend a lot of time, it's worth exploring the possibility that mold may be a contributor to your heartburn or acid reflux problems. Google "black mold" to find sites that can instruct you on getting rid of the problem (unfortunately, it can be a pain in the rear, especially if you live in a damp climate where it's pervasive), and in the meantime, pick up an air purifier strong enough to destroy mold spores in the air.