I Have Had An Extremely Bad Cough That Just Seems

I have had an extremely bad cough that just seems to be getting worst.. my daughter actually started out with it then transfered it to me..Her doctor has uped her med twice in the past month and nothing is helping. It feels like if we breath it to fast that our lungs shake and we go into a coughing fit, it's been going on for a little over a month. I have tried humidifier in the room where we sleep, she is still on her medicine and I have been taking over the counter cold and flu and it's not working.. Any advice?