Coughing colorless phlegm, stuffy nose and irritated throat. what is the cure? thank you!

Hydration: you need to stay hydrated, most likely you are having some kind of allergy, Hydrate yourself well, and you can take OTC medicine for congestion, and cough, like Zyrtec ,or Claritin, or Allegra, Benadryl (diphenhydramine) at night, mucinex for cough, ibuprofen for fever, or body ache. Drink a hot green tea with lemon and honey . Get plenty of rest.