If you are breastfeeding than smelly poops would be unusual (smelly
farts are very normal -
my son is exclusively breastfed and his gas could level a grown man!). If she is drinking formula, than her poop will be smelly, but I am not sure about a sulphur smell. I would check with your pediatrician, as sometimes certain smells can indicate a medical problem (for example, urine that smells like maple syrup).