sounds like allergies to me. itchy throat is one symptom of allergies....also when your sinuses drain...it goes to your stomach and can cause it to feel upset. coughing....there is such a thing as coughing asthma brought on mostly by allergies. How do I know all of this???? Both of my kids..ages 14 years and 11 years...has terrible allergies....and this is exactly what happens with them. And I have dealt with this since my oldest was 5 years old. I would try some benadryl daily to see if that helps....if not, you may need prescription medicine. You can also request to be allergy tested to find out what all you are allergic to....to see if there is any way that you can control being around things you are allergic to. good luck.