@browncoat - I would suggest that the next time that happens you do go to the doctor. Even though it is probably self limiting (meaning it will go away by itself) your eyes are quite vulnerable when they are that swollen.
So, they could easily get an eye infection if they don't go down very quickly. And dealing with an eye infection on top of an allergy would not be fun and could lead to permanent damage of your eyes.
I'm always one to err on the side of caution, but especially when it comes to my eyesight. Almost any kind of chemosis seems like it should be checked out by a doctor.