It is treated and resolved itself. Not meds for over a year. Just not sure if I check the box in 18
By saying you did take meds in the past for it, then it definitely is a "have you ever in your life..." sort of thing as it is in your discoverable medical history.
So if it is resolved as you say, mark it as yes, explain the details in the area that allows you to provide more info, and obtain a short and simple status letter from your treating physician that confirms what you said. Something like
Mr. X presented with GERD on mm/dd/yy and was treated with name_of_ medication, dosage, frequency. During treatment, he tolerated the medication well with no side effects. On examination mm/dd/yy, I determined that the GERD situation had resolved itself, and medication was ceased. On his most recent examination of mm/dd/yy, Mr X continues to show no signs or complaints of GERD symptoms.
The AME will likely see the box marked yes, read your explanation and the doctor letter, ask you some questions, then yawn and move on to the next item on the list.
But if any questions regarding your medical application ever exist and you cannot resolve before seeing the AME, always ask for the visit to be in consultation mode (and keep the confirmation number in your pocket) and not a live exam. If the AME says he is not able to issue right then and there, then discuss what is needed to get you issued on the spot and come back when those items are done.
If during the consultation, the AME says he can and will issue you right then and there (no deferral or denial), then and only then surrender the confirmation number