I've had two episodes where I was walking that I felt like I burped acid from my stomach not quite to my throat. No other pain at all, but I suddenly felt faint. It made me sort of panic and then my legs felt heavy and weak. Within a few seconds (10 or so) I felt normal again, but sort of vulnerable to it happening again. No lasting pain anywhere. I'm male, 60 years old, 5'11", 170 lbs. and above average fit. Should I be worried?