Still sick after 3 weeks...

I got sick 3 weeks ago. Called into work for the first week while it was really bad. Fever, deathly cough, and it felt like I was drowning because of all the mucus in my lungs. I saw a doctor, and he said it seemed like the beginnings of bronchitis, and thought it was viral. So he didn't give me any meds because he thought it was viral. I went back to work the next day and I've been back for 2 weeks. I'm still coughing. The fever is gone, sometimes at night it will go back up to a low grade for a bit, but its always gone by morning. I was getting better for a while, but now I feel like I'm coughing more again, and I'm constantly coughing up dark sticky mucus from deep in my lungs. Still no fever any more, and no other symptoms. Just deep chest mucus, and rattling/whistling. It's not painful or anything, and never was, but it's getting so annoying having so much stuff in my airway, and always coughing. Is it normal for bronchitis to last this long? Should I go back to my doctor?