First let me say that I know NOTHING about plumbing. I did however just read an article in the paper by "Ed the Plumber".

If I recall from my chemistry days, sulfur smell is the same as rotten eggs. This was his advice.

"Have a licensed plumber check out your water and water heater. A rotten egg smell usually points to a water issue, and many times the anode rods in a water heater can break down and react with your water to provide strange odors".

You should chlorinate the water. I went to the below listed web site and found I needed to chlorinate my water to get rid of the sulfur smell. I also had some iron that was too much for the water softener to handle. Chlorination takes care of both. I had a local well installer come out and he agreed with this assessment.
I now use chlorine injection, then a contact tank to allow the chlorine to react with the iron and sulfur where it settles out of the water. Next is a carbon filter to take out the chlorine, then a water softener.
My tap water now tastes like what comes out of my under-sink Reverse Osmosis system.
Check out this web site. They have really good technical information. I bought my stuff from the local company, but if I were installing myself, I would have ordered it here.

Here is a link that might be useful: cleanwaterstore