persistant productive cough

approximately 2 weeks ago i went in to the doctors for an extreme soar throat and stuffy/runny nose. the doctor checked to see if i had strep throat and the test came back negetive. He put placed me on amoxicilin because he felt that it was going to develop. 3 days after my visit i develop a productive cough. i began to take expectorant. last week i went in to the doctors again because i wasnt getting anybetter. he then put me on a medication for my nose and cough. it made the symptoms less severe but still they remained. until now i still have a runny nose and when i cough it doesnt produce much phlegm but it takes twice the effort to cough it out. i dont know what to do anymore. im definitely not getting worse but i dont feel like im getting any better either. should i go to a different doctor and see what he suggest? as of now im taking a chinese cough syrup. i just started taking it so i cant tell whether it's working or not. someone please help, i feel like i have reached a dead end.