Of all the health problems, why would I get gerd?

No info to evaluate. You get the most from this site when you provide background information and ask a specific question. Questions without background remain too vague to answer in the space allowed. Do you consume caffeinated products, smoke, lay down after meals, etc, which all aggravate GERD? Do you take meds for other health issues? You are welcome to start over but realize your posts are not linked.
GERD is common. You're in good company--70 million in usa. Stomach stuff (whether acid or not) regurgitates back into esophagus--due to inappropriate relaxation of lower esophageal sphincter, impaired esophageal function (peristalsis), inadequate saliva, gastric outlet narrowing, gastroparesis, small bowel pathology, etc. Damage to esophagus may result including ulcers, scarring, narrowing, pre-cancer (barretts).