sinus infection, possible dental issue - did you ever have a root canal? can also be upper g.i. issue
Do you have allergies? Also, are you having difficulty with your spit being too thick? If so, this could be a saliva gland problem. You should see your doctor again and see if it is seasonal allergies or something more serious.
Hello,
It could either be allergies which can cause the phlegm to form. I always have phlegm in my throat I was told it is due to a combination of allergies, asthma, and sinus issues. I get a lot of sinus drainage in my throat and ears almost all year round. Try taking an over the counter zyrtec or some other form of allergy medicine first. If it doesn't help try some sort of mucus medicine. Also talk to your primary care provider about it.
God Bless,
Dustin