It seems that you are going through common cold symptoms such as a continuous cough when lying down and an increase in saliva. These signs usually result from nasal congestion or irritation of the throat. Even though antibiotics are efficient in destroying bacterial infections, they will not have any effect on viral diseases such as the common cold. There are also easy remedies available for OTC ones and combination with good hydration will relieve discomfort. If can't recur, if you encounter shortness of breath, or if you continue to have too much saliva, please confer with a pulmonologist for a complete review. Always, assuming the proper course by asking for good advice is a good way to get the right information and care.