it always helped me to eat before i went to clinical. i have a real hard time eating at 5 a.m. but the one time i didn't, i was heaving in the bathroom.
another thing that helped me was talking while doing something that had an odor attached to it. if it was cleaning BM, i just tried to make small talk with the resident whether he/she could respond or not. hard to get a gag reflex going when you're using your throat for talking. :chuckle
another thing that may help is peppermint oil. put a dab on a tissue and carry it in your pocket. whenever you're feeling overwhelmed with the smells, just pull out the tissue and sniff.
i've also heard the same thing about smelling coffee. now how you could carry used coffee grounds around in your pocket all day is beyond me but i'm told it works.
try to stick it out if nursing is what you really want to do. there will always be certain smells in any field of nursing but the "LTC facility smell" is very unique. you won't be there forever.