If your hot water still smells like rotten eggs even after sanitizing you may have to add some white vinegar to the water heater tank and let it set. It is recommended to remove the relief vale to pour it into the water heater tank, but you could also use the winterizing connection to pump it into the tank by opening the nearest hot water faucet to the water heater.
Drain the water heater first before filling it with 2 parts vinegar one part water. So for a 6 gallon water heater tank you'll need 4 gallons of white vinegar. You'll need a little extra if you use the winterizing connection but don't have to mess with removing the valve. This will also help to descale the water heater if it's needed.