Change the anode rod to one of a different type and you'll probably get rid of the smell. The hard part is getting the old one out...an impact wrench or a big wrench and someone else holding the tank so it doesn't rotate is often required. If you don't have much room vertically, they sell 'segmented' replacement anodes that can be bent so you can install them. You may have to cut or break the old rod as you take it out (just don't drop it back into the tank!), since it is likely a single solid rod.