For a deep chest cough i would try some Vick's vapor rub on your chest area & something that will also soothe the back of your throat too.. laying down i heard can make the phlegm worse so maybe prop up on some pillows??
No suggestions, just know what your going thru. I've got the cough that doesn't really want to leave, it has caused me to nearly throw up a few times, so thankful I was able to keep stuff down. I've ended up on a new inhaler because of it, shortly before finding out I was pregnant.
The robitussin dm will probably help the cough, if it sticks around for you may want to check with your doctor.
Smh must be a bug going around Im sick now since last thurs feel kinda better tho! Get soup & crackers, halls, caffeine free tea I use peppermint tea..orange juice, ginger ale & im takin Robitussin dm
Have some cough drops and Robitussin DM.