i developed reflux for a while because i was eating fast my entire life. my grandmother joked that i would do well in the army. now i cannot eat in the evenings, or else i have to take a walk, sit up for a while, or sleep in a reclining position.

so i second the advice of smaller meals and a walk immediately after. the puppy's stomach should soon outgrow this issue. watch out for quality of poops and general energy levels, of course.