Feel really nauseous, especially after eating?

Recently I have been taking pain killers for my back called co codamol, with side effects including nausea, however I stopped taking these three days ago, and I still feel sick, and I can't eat without dry retching. A few days ago, my friend served me chicken which tasted funny, and we looked on the packet and it was a week out of date. I also feel really hot, possibly a fever, please help