I had what I call a pulmonary trifecta about 12 years. I caught whopping cough and influenza B while sailing Lake Michigan. (Unbeknownst to us one of towns was in the early stages of a whopping cough cluster.) The combo led to mycoplasmic pneumonia. I am extremely sympathetic to the miseries of awful spasmodic coughing. Having noted that, I would be extremely cautious about taking too much Dayquil and Nyquil, yet alone along with other stuff. These drugs that address a plethora of issues that you might not even have, e.g., multi-symptom cold 'remedies', have issues including cautions about glaucoma, liver, etc.

The only thing that worked for me was hydrocodone. Which is unfortunate as politicians decided it should be way harder to get in many states. So it would now take someone with my pulmonary trifecta an office-visit to get, and the prescription would be limited to 72 hours worth and needs to taken to pharmacy, in person, by the pneumonia-afflicted, already-weak person. Thereby ensuring that others in the doctors' waiting rooms, office, and pharmacy exposure to the bug as well. How can that possible be in the interests of public health?

I'm keeping the Tessalon perl thing in mind if I ever might need it.

I would add one thought. Sometimes a dry, aka "umproductive" cough, is similar to a muscle spasm and muscle relaxants can help break that response...