Bronchitis just won't go away!?

Four weeks ago I had bronchitis with green phlegm, and was prescribed penicillin for a week to treat it. I felt a little better, but within a week I was coughing up green gunk again. I went back to the doctor, and got a two week prescription for amoxycillin. I felt almost normal while I was on it, but now four days later, I am once again coughing up yellow phlegm with a low fever. I know last time I went to the doctor she said she didn't want me taking more antibiotics, but do I need them if the bronchitis hasn't completely gone? I live in New Zealand, so we don't have mucinex here, although I have been taking cold and flu tablets. I'm just sick of being unwell!