Recently had our bathroom redone, (new walk in shower, bath tub, floors, counter, sink, etc.) now when we shower (after it has been turned on for about 5 minutes) we get a sewer smell that comes from the drain, it continues after the shower is turned off filling the smell through our entire bedroom. The plumber just put a flapper in the drain now I think the smell is worse and our shower drains slow. Previous to the construction we had an enclosed shower and no smell

Sounds as if p-trap from original drain was removed and not replaced during remodel. The p-trap keeps the gas odors from coming through drain lines.

Thank you for the quick response, I have sent this information to my contractor. I sure would think the plumber could have figured that out, maybe he just doesn't want to admit he made a mistake

If the installer had left the trap off you would be smelling sewer gas from the git-go and for 24/7 every day. Is that the case here? If not then you just have a smelly drain.
Most bad odors in bathroom drains come from rotting hair mixed with grease from the soap. Try this. Remove the two screws holding the strainer. (TIP; put the screws in the soap dish before they get lost down the drain.) Shine a light down there and with a bent coathanger fish out any hair that may be hiding down there. Then pour a 1/2 gal. of bleach down into the trap and let it set over night. Next morning flush the mess down with 2 large pans of boiling water, (this is important). The bleach will dissolve the hair and make it slippery and the boiling water will melt the grease and get the mess out of your drain. Smell better now? Cheers TOM