Question: my baby is 5 months old and just got over a stomach virus and a runny nose / cough, she's…

Question: my baby is 5 months old and just got over a stomach virus and a runny nose / cough, she's been choking on her saliva because it's so thick, doctor has me watering down her bottles so the milk isn't so thick, but she coughs and chokes all night. My question is .. What can I do to help her , and does the Vicks on the feet really work? Has anyone tried it ?