Hope you get better soon. Must say it seems strange that you are on second lot of antibiotics after 3 weeks- as most of the time GPs will not give antibiotics for about 10 days, as it is normally a viral infection. With bronchitis, research shows that taking antibiotics early can make things worse in long run.
Had the same for 5 weeks, then got antibiotics on 6th week- finally got over this.
I know you say you haven't got time to take time off and rest- but your health is so much more important, really. Steam 4x a day with Olbas or similar oil is the best way to get rid of this, and plenty of hot drinks + hot toddy at night.