6 mths ago i ate food that gave me food poisoning, diarrhea and vomiting. it was over quickly, but the odd smell of that diarrhea still exists when i have a bm and gas. it is very bizarre. could i have a parasite? im other wise healthy?

It is likely that your bowels got colonized at the time you had the food poisoning with a conditionally pathogenic bacteria rather than a parasite which is still definitely possible. If you have any reason to believe that it is indeed a parasite, noticing unusual particles in the stool or having specific symptoms, having your stool checked for ova and parasites would be best.