I would suggest that you have your thyroid levels checked. I was diagnosed with Graves Disease ( Not nearly as scary as it sounds!!!) about 20 years ago and one of the symptoms of it is constant throat clearing. It is caused by polyps on your Thyroid...which sits in your throat region and I guess it makes you feel like you have something that you need to clear from your throat all of the time.
Your thyroid is the "thermostat" that regulates all of the phsycial activities of glands, brain, and organs. Depending upon whether you have Hyperthyroidism ( Over active thyroid production) or Hypothyroidism ( under active thyroid production) you would experience almost opposite symptoms.
With Hyperthyroidism you could expererience heart palpitations, jitteriness, diarrhea,sleeplessness,hot flashes,excited speech,
With Hypothyroidism you could experience Constipation, Lethargy, Being Cold all the time, slowness of thought and speech.
Your doctor is the only one who can test for this....go to him with your concerns and see if he thinks the Thyroid might be the culprit. If it is...it is a really simply "cure"...they killed my thyroid off with a radioactive pill and now I am on a daily dose of artificial thyroid...case solved!!
Good luck to you