Bad cough

Hey girls, As you all know there is a bad cold/virus doing it’s rounds we have all been loaded and tbh I’ve never had a cold like it in my 33 years lol. My son has got over it but his cough doesn’t seem to be budging he’s now had cough 16 days, I’ve given him cough bottle and tried the calpol plug in and vics on his feet nothing seems to budge it.