how deep is your sandbed? When you say you stir it, how much? There have been problems in using sand in tanks, as it can have anoxic areas in them, which can lead to the smell your describing. Actually, it's kind of a dead giveaway, as there aren't to many things that smell that way in fishtanks. I would recomend removing the ebjd to a temporary holding tank (or a bucket for you technophiles) and stirring the sand bottom thouroghly. then, do a massive water change. After the tank has settled down some, use your nose. If it smells clean, it's safe for the ebjd. A couple of things to think about for the future, add some malaysian burrowing snails. They will help aerate the soil. Also, a loach will help with that, especially the kuhli loaches.
If your doing some of this stuff, great, stir more and deeper I quess?
If your doing some of this stuff, great, stir more and deeper I quess?