I am looking for help from some of the plumbers that may frequent this
board.

For several months I have been getting a strong hydrogen sulfide smell
from my hot water. I have drained the water heater several times. It
gets better but then comes back quickly. I know it's not bad city
water because the cold side is fine. When I drain, black gunk comes out
for a few seconds and then clears. I have even drained it completely.

I am worried about the health concerns.

Has anyone heard of this? What is the cause? How do I cure it. Any help
would be appreciated beyond your imagination.

Thanks