3 month old baby has nasty cough

My little 3 month old has a really nasty cough and I don't know what to give her or what to do with her. Her cough is so bad that when she is asleep she coughs hard and wakes herself up and then falls back asleep. What can I give ? Or should I make an appointment and take her to the doctor? Any suggestions ? Or any home remedies that I can do ??? 
Please let me know 
Thank you-