Suggest Treatment For Cough With Retching

I have had cold symptoms for a little over three weeks now. I quit smoking 2 weeks ago. I made sure to drink plenty of bottled water through all of this time. The symptoms I have experienced before medication were nasal congestion and a mild cough.
After two weeks from the start, I began to cough uncontrollably until I retched and vomited for hours. I was prescribed mild cough syrup, a pack of steroid pills, and a z-pack. On the second day of taking those meds, my cough became uncontrollable again along with more frequent episodes of retching. I was so nauseated and had extreme cold sweats. I could not eat at all for those two days. I decided to go to the emergency hospital. They took an x-ray and said they couldn`t find anything serious (assuming they meant pneumonia) or a mass. They told me I seem to have an upper respiratory infection. They gave me a tussionex(hydrocodone) extended solution and zyrtec-d extended pills. I stopped taking the old meds and began the new meds. I have been using both every twelve hours for about 5 days now. Symptoms went away almost completely except for a mild cough for those 5 days. Now that I am out of hydrocodone, my cough has come back uncontrollable as ever along with the cold sweats. They said I should be better by the next week but I'm not. The meds only masked my symptoms. It starts as a stinging tickle in my throat... like something is in it. Something is wrong with my throat or something in it. The stinging tickle gets worse and causes the uncontrollable coughing which creates retching. I need this to stop. I can`t eat or sleep. I am completely miserable. What do you think is wrong with me and what should I do about it? Also note: I have been diagnosed with GERD a couple of years ago.