Chins cough

My chin (fushi) started to cough every 2-3 min.. (my other chin started to cough as well but much more rarely) now from a phone call with the vet he seem not that worried and says i can come in 2 days and to give them 2-3 drop of cough syrup... i never heard of anyone giving that for chins so i would like to ask you guyz.



also they have no runny nose no wettnes from the eyes or ears and such, they do seem to eat a bit less and he gone down weight (6 grams... not much but still).