Ahh yes the infamous rhino farts, so in a short answer yes it is supposed to smell that way
It will pass after 2 or 3 days so not much to worry about there. As for the fermentation taking off rather quickly, that is pretty much in the norm as well. It starts off pretty quick, but can take anywhere from 4-6 weeks to fully finish. If you have time read the whole Apfelwein thread, there is a wealth of information in there.