believe it or not my partner had this a while ago, apparently it can be from undigested food being stuck i'm not sure about pregnancy though, i read that if he drank milk not water it would help as sure as fate after 2 days of drinking milk and watching what he was eating it disappeared, i hope this helps u
The only thing I can say is that whether I am pregnant or not, if I burp that egg taste, I know soon I will be vomiting. I think it's from the gas and the bile.