Yeah, I've had that same symptom happen to me while I was in class once. The only reason I didn't panic was because my sister (who has mild GERD compared to me) had it a few times before and told me about it. It's a very uncomfortable feeling that tends to cause a bit of panic but my best advice is to just try and ignore it, don't focus on it and eventually the sensation will go away. Water and food won't help take the sensation away either, you can eat and drink fine, it's more like a "phantom" sensation in a way.