Are your pipes copper? If so there could be a hard water build up in them. The only way to really get rid of it would be to install new pipes. It worked for us. We had a bathroom sink with very old pipes, once we replaced them the smell was gone.

What you are smelling is Hydrogen Sulfide, H2S, rotten egg gas, the source is your water and not the pipes themselves, though the action of the H2S on metal can damage the pipes and cause a stronger odor. H2S can also react with hard water scale build up in the pipes. H2S is poisonous, but not in the amounts that are likely to be present in normal water supplies, its just stinky. In fact H2S actually deadens the sense of smell when it approaches toxic levels so if your taking a stinky shower someday and suddenly you don't smell it anymore get out of there or just take the clothes pin off your nose and rinse and apply again just as you were doing. Are you getting your water from a private well? There are some otherwise inoffensive bacteria that can live in wells and give off H2S and other sulfur compounds, a disinfecting shock treatment may be needed. I think if you had a well you would have mentioned and considered it. H2S is a naturally occurring compound easily dissolvable in water and present in nearly every water supply in America. Usually it is such a small amount that it is never noticed. In places with high content it is often removed at the treatment plant, other people install various home filters. At certain times of the year, usually late spring, early summer and sometimes again in late fall water from reservoirs may have an increase in odors or even tastes including sulfur due to the lake 'turning.' The water absorbs heat but the surface remains cooler eventually the warmer deep water rises bringing nutrients which cause an increase in plants, some of which release sulfur, but more importantly it also brings up those bacteria which have been spending most of the year happily producing sulfur. In the fall there may be another turning as the water up top cools faster than the deeper water. If your sulfur shower is seasonal that may be the answer. But I suspect the water heater, especially if it is around ten years old. The H2S is probably present in all your water, you notice it more in the shower because you are spraying a lot of water into the air and a lot of that lot of water is hot. H2S is easily dissolvable in water but when the water is heated H2S is released as a gas. In fact as the water heats in the tank H2S is released in there, when you open the tap the water brings not only its dissolved H2S but some of the free gas, as more water comes in it too releases gas. Over time the heater concentrates H2S in the tank. Some gas rises to the top of the tank above the water outlet, but since the water in the tank is basically under pressure most of it is redisolved in the new water coming in. When you open the shower valve you release the pressure and the gas escapes, peeeyewww. I betcha if you go in the kitchen and run hot water really fast for a while and sniff close you will detect H2S. Try running your clean and empty dishwasher, or filling your clean and empty washing machine with hot water and taking a sniff. You may have to install a filter at the water heater inlet to keep the gas from getting in there in the first place. You may be able to at least alleviate the problem by draining and flushing the tank real good, especially if ya haven't been doing that yearly,... hmm that reminds me.. You might be surprised at the amount of sand and other stuff in the bottom, that can act a sorta sponge and hold even more H2S as well as, in extreme cases, give a home to certain bacteria which are releasing more. Check the sacrificial anodes, if they have made the ultimate sacrifice, the water is now attacking the tank itself which can also release H2S and other sulfur compounds. Be warned though that draining a tank that hasn't been drained for years can doom it. It seems like flushing all the gunk in the bottom out also flushes away gunk that has been plugging a pinhole. Sometimes the gunk itself acts sorta like a sacrificial anode itself. The water attacks the tank now. Actually the tank is doomed anyway, at least this way it'll spring a leak while you are still thinking about it, maybe expecting it, and can turn the supply off instead of in a few months while you are off relaxing in some spa enjoying the hot sulfury smelling mineral baths. Wait a minute! You have one of those already! What are you complaining about? You may have to replace some pipes as mom did. Especially if they are older copper ones. They've made some changes in the formula of the copper, older copper combined with some of the minerals in hard water reacted with the water and caused a release of the H2S, replacing older copper with newer formula or even one of the plastics rated for hot water might help. Just one more thing to check B4 I let you go, I mean you're standin there drippin all over the floor. Check the drain in the shower, H2S and other sulfur compounds are part of sewer gas. The drain, trap, or pipes may be partially clogged or damaged generating gas or allowing gas to rise and getting all stirred up when you turn on the shower. I doubt that actually, either the shower would stir up so little gas that it would soon dissipate, or there'd be so much gas you'd smell it all the time. One last thing to check, I almost forgot. Check to see if the Answerbag's rabbit or one of your kids, didn't cram an Easter egg up the shower head last year and forgot all about it. Wascawee wabbit!

Run out all of hte hot water from your hot water heater. Remember to turn off the water supply to your water heater and also turn off the heater itself. OR get a new hot water heater! OR call a plumber.