Eggy burps!!

[PinkyDink]

I know this sounds odd but my 7yr old DS had some 'eggy' smelling burps on Sunday along with tummy ache, he then threw up a couple of times and has been ok until today. They have started again along with the tummy ache.

Anyone else experienced these?

I know this post is a bit old, but I had the same with my daughter 19 months. She had eggy burps followed by throwing up (three nights in a row). That was about a month ago, but just today she has started to have eggy burps again.
Is it contagious?? A viral infection? It's just that I thought you couldn't get the same viral infection twice?? I was also wondering if it could be got from drinking water out of old bottles? Any advice would be good, as I don't want to spread it to any one else.