Don't worry, Mike, your doctor has got you covered. You've given a very nice description of hives, including the fat lip, which represents fluid deeper under the skin than what there is in the regular hives.
Hives come and go at random. They tich like crazy. They can be aggravated by pressure. Most of the time they are caused by nothing--not allergy, stress, or the rest of the usual suspects. I'm not surprised the blood tests your doctor ran were normal, though it's reassuring that they were.
Eventually (weeks, months) the hives go away as mysteriously as they came, though they may come back years later. You might want to ask your doctor to consider increasing the dose of Allegra to 60 mg twice a day, or 180 mg once a day. That might help suppress the symptoms a bit better and if not, there are other antihistamines to try too.
Best.
Dr. Rockoff