Girls, my cough hasn't gone for three weeks now, I've been taking…

Girls, my cough hasn't gone for three weeks now, I've been taking antibiotics (Clavam, Megasef) but it doesn't help, I gargle constantly, and it seems worse every day. I do inhalation therapy. My daughter (8 months old) also had it, but she was cured, I can't seem to get better myself. What could help?