Thank you, All, so much for your time and helpful advice!
Okay, we did something yesterday that may have been foolish but at the time his cough had gotten bad and after spending so much on vet bills and prescriptions, we decided to invest in a bottle of infant cough medicine. We gave a small dosage to Mack and after coughing up a big glob his coughing has subsided and he appears to be feeling better.
We won't be repeating the dosage.
I do love the idea of elderberry and honey! However, our fear of negative results after trying the infant medicine had us so on edge that if Mack does start coughing again, we will call the vet.
Thank you all, again! I appreciate you!!