Old-Biscuit wrote:
Are you sure it is coming from the 'water' and not coming up out of sink drain ???
Pull 'P' trap and clean out the gunk
This would be my guess too. There shouldn't be a reason stinky water only comes out of that sink and none of the others. But it's possible when you run the water it stirs up the water in the sink trap and maybe that is where the stink is coming from. I have seen on here where people have stated their bathroom sinks drain into the black tank. So you may have some type of black tank backup.
I have had stinky water before caused by the water heaters, but it comes out of all sinks, not just one.