how do i know if my chest infection is gone?

Hey guys,Sorry i havent been on the boards much. Makes me feel bad for posting. This year has been a rough one.Basically i caught a cold about 3 weeks ago. and have been coughing, mucusy etc since.. Last thursday i finally went to the docs, got told i had a nasty chest infection and prescribed antibiotics. they were finished wednesday night and now although feeling a lot better than i was (cough hurts less, less productive.) I'm still nowhere near 100%. Lungs are hurting, tired, still got cold symptoms and although coughing less still mucusy. But my peak flow is ok at 410 (PB. 470). so is it worth going back and asking doc if i need more antibiotics? or do i need just to wait a few days and let my body work?Just fed up of being illJen x