I'm a medical student at Pitt Med. I suffer from the same problem you do. I believe it is highly correlated to my stress levels (which highly correlate to my breathing rate). Read the "theory" section in the below article:
http://en.wikipedia.org/wiki/Buteyko_method#Clinical_Studies
In short, breath more --> decrease CO2 in the blood --> produce more mucus --> clear throat --> cause faster breathing --> make the problem worse. Repeat the cycle over and over. What we need to do is simply breath easy for long enough for our bodies to normalize again. I've been trying it for a while and it seems to work like nothing I've ever tried before.
Also read this published paper:
Hyperventilation: a review
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1290766/pdf/jrsocmed00176-0035.pdf