Sudden Throat Swelling That Goes Away With Water

[Kathy16846]

For the past few weeks or so, every once in a while my throat will start to swell with no obvious cause. It gets a little hard to breathe and swallow, but it usually goes away by itself after a few minutes. If I drink water it goes away immediately. It seems to happen more in the morning or very late at night.
I'm a nineteen year old female with no known health issues, allergies, or taking any medication, and I'm not currently sick (in fact I almost never am). It's my only symptom of anything; no obvious swelling, pain, fever, dehydration, etc. If it didn't come and go so quickly, with no warning or other symptoms, I'd say it was some kind of infection or tonsil problem.