We need to start tracking these water problems so I need to know what state you are in and do any of your neighbors have the same problem? I assume you are referring to a rotton egg odor in your water. What was the condition of the initial rod when you took it out and how long was it in the tank?
Do you have any other other symptoms, such as bacteria in your toilet tank or toilet and any black or brown material coming out of your plumbing.
The first thing you need to do is have a qualified plummer chlorinate both the hot and cold water plumbing. That means putting bleach in the entire system and letting it sit overnight. You need to remove all screens and filters, because if there is bacteria living in your plumbing, it will plug up the screens. It could also plug up your mixers in the shower. You also need to protect all of the chrome fixtures when flushing the system, because the bacteria produces a black slime that is highly corrosive and it will eat the chrome before you can wipe it off.
You need to get more than one estimate, as some plumbers overcharge for this service. The cost can range from $200 to $800.
The fact that the house was new in June 2010 indicates that there is a bacterial regrowth in the distribution system. This not uncommon.
As you have discovered, changing the anodes is not the answer, in fact, the magnesium anode increases the activity of the bacteria, and a water softener makes it worse.
I am sure you will have more questions and if you would like to discuss it over the phone, give my your phone number and I will call you.