12 month old with chesty cough, wheezy in morning, and waking up at night

My 12 month old daughter has had a cough for 3 weeks now. She picked it up from her brother (who's cough went on for 6 weeks!),but hers seems worse. It started with some nasal congestion, a very slight, clear runny nose that would run very little. the cough came about 1 and 1/2 weeks later, and it was a severely dry cough that would mostly happen at night.

now, after about 3 weeks of coughing, her cough has turned wet and chesty. there is some wheezing and gurgling in her chest in the morning. the cough is now not only at night, but in the day now too. she wakes up at night at around 11pm, then around 3am, then around 5am. she used to sleep throughout the night, but not for a month now, when this illness started. also, she has a more clear, runny nose since the wet cough started.

please help, she doesn't feel well, plus it has been too long with both children, and i have had very little sleep for about 2 months now!!!