Hi
As you mentioned that you are having dry throat ,cough ( severe bouts) due to cold and sometimes  you have to spit saliva ( in my opinion this may be mucus or sputum due to cold). 
However all these symptoms , mentioned by you may be due to 
allergy . 
As allergy causes 
bronchitis and 
bronchoconstriction produces cough ( as in your case ) . Bronchoconstriction   produces cough and saliva or sputum . 
This is cause of concern but don't worry so much . 
Mite , dust , pollen , mold , hay , smokes , fumes , sudden rise and fall of temperature are few predisposing factor responsible for allergy , hence all symptoms . 
I usually prescribe monteleukast + bambuterol ( if asthma or 
wheezing present ) , if whistling sound don't present I advise them to use monteleukast+ 
fexofenadine or levocetrizine  twice in day till complete cure.
Good luck.