Shower drains normally do not smell, so the smell of sulphur coming from your shower's drain is a cause of concern. Putting chemicals or other liquids down the drain likely will only mask the smell temporarily, not solving the root of the problem.
The P-trap sits under the shower's surface and works to keep any sewer smells away from the shower's drain opening. If the person who installed the shower did not use a curved trap piece, the water that enters the shower's drain will simply run straight down the pipes. Shower drain systems with a trap keep some of the water in the trap. This water acts as a block, not allowing sewer smells or gasses to pass through the pipe and make their way out of the shower's drain opening. The trap only works, though, if you use the shower often enough to keep the trap full.
The vent pipe that you can see from the house's roof introduces air from outside into the bathroom's plumbing system. The vent pipes normally do not clog, but occasionally a bird may build a nest on top of a pipe or the pipe itself starts to break apart and crumble inside itself, causing a blockage. With the vent pipe blocked, the water levels in the different plumbing devices will start to change, emptying out the trap in the shower's drain system.
Over time, debris such as old skin cells, skin oils, soap scum and such will collect on the walls of the drain pipe in your shower. Slime accumulates on the pipe, before reaching the P-trap. The bacteria contained in the slime starts to smell, which can smell like sulphur or the sewer itself. The solution is to clean the walls of the pipe with soap, water and a bottle brush.
As with any plumbing problem, contact your trusted plumber for help if you cannot find the source of the sulphur smell or if you realise you are in over your head. A plumber can send simulated smoke through the house's vent pipes to find a leak. Plumber's have other tools, knowledge and experience they can use to see the problem to a resolution.