Septra DS and vomiting

I am taking Septra for a sinus infection. I am consistently, ridiculously nauseous all day and all night since within two hours of my very first dose. Taking this medicine with lots of or little bits of food, milk, bread, soup, peppermint tea, ginger, etc. doesn't make a difference.
Food smells make me wretch. I can't even wash the dishes because of the leftovers. Even simple mention of some foods makes me gag.
I also am sick when the road curves too much ahead of me, I see spinning things, and moving my eyes too quickly.
I have never been this nauseous in my life. I find it disturbing.
Vomiting does not relieve the sensations. My vomit tastes very bitter.
I suspect the accompanying headache is from dehydration caused by the low food intake and diarrhea.