I Have RA And I'm Taking Sulfasalazine And Paquenil, I

I have RA and I'm taking sulfasalazine and Paquenil, I have been given Cepro antibiotic from 10/10 to 10/20/16 I had a flu shot on 10/13/16 I started to feel fatigue and weak a week ago I started vomiting and no appetite . When I eat or drink liquid I started to cough and sneeze then followed by sense of vomiting or actual vomiting. I vomit clear sticky mucus with some liquid. What do you think is the cause of my gastro problem?