Obviously, no diagnosis can be made at distance, but, if you find the coughing increases when you lay down and especially if you are experiencing a stuffy nose or sinus drainage, try spraying, several times a day, with a simple saline solution available at any drug store . It's made especially for this and contains no medication. The brand I use (here in the U.S.) is called "Oceans". Most coughing as well as sore throat, I've learned, is caused by sinus drainage and if you can keep them well irrigated it should help. Best of luck...