In the tannery we remove Hydrogen Sulphide from a pH ~9-10 water by bubbling air in the presence of manganese sulphate and add a bit of Hydrogen Peroxide to keep the reaction from reversing in anaerobic sewer condition by bacteria. This might be a bit drastic for you but I have found the following which might help.
Treating Sulfur Water
Natural Handyman's Removing Hydrogen Sulfide H2S From Water Page
Pond aeration well water aeration and sulfur removal through aeration.
As mentioned in the links, a source of H2S can be bacteria which break down the sulphate to H2S, if I'm not mistaken. These can be killed, or shock treated, as they call it, to lower the population density. Total eradication is however not possible. So it might be worth your while to have the well checked and treated, if this specific bacteria are present. A friend of mine used to run a field of wells to supply water to a local community. The water they extracted were found in Sandstone and had a pH of about 5.0. They had to pull the submersible pumps, lines and remote control valves and the telemetric flow modules quite regularly to clean out this bacteria which reduce the flow of the water by quite a bit.
