If your water starts to take on a sulfur or rotten egg smell, it’s likely the anode rod, as Bill stated. I would check that first. If that still looks good then I’d sanitize the water heater.
Not a dumb question at all! Its actually one many people can’t agree on. In my experience, and after reading several owner’s manuals for Suburban and Atwood water heaters, it’s recommended to sanitize with either bleach or vinegar. Check your water heater owner’s manual to see what it suggests.