I am reaching out to you because I am at a loss as to what this issue is, my vet is stumped as well.
I have a 5 yr old PB with a history of allergies. This past May, he woke up with a lump, a swelling right below his eye, along his jawline. I figured it was a tooth issue and took him to the Dr. The Dr could not find a prob with his teeth and told me it was probably a spider bite. He gave Collin an injection of anti-inflammatory/anti-histamine which seemed to do the trick. About 6 weeks, he has another swelling, exact same place. I take him back to the Dr, it can't be a spider bite in exactly the same place, can it? My Dr could not find anything wrong with his teeth, again suggested it was a bug/spider bite and gave him the same treatment. About a month later, same swelling, same place. This time I did not take him in, treated him at home with the anti-histamines I keep stocked with for his occasional allergies (he gets hives occasionally and itches terribly. The swelling was completely gone by day 3. His next flare up coincided with his yearly vet visit, and again my Dr could find no other explanation for the reoccurring swelling, each time in the same place, right below his right eye, along the jaw line.
We live in MD, and the last episode took us into fall and cooler weather, and he hasn't had a problem since then. Until today, when I noticed a slight swelling. I took a peek at his teeth/gums and they seem ok. At it's worst, the swelling is big enough that it almost closes his eye, but it isn't tender, he doesn't itch at it and it doesn't seem to bother him. Eats and drinks just fine, no other symptoms. There are no other changes I can think of, like I said he does have allergies so I keep everything around him pretty consistent with food, laundry detergent, etc...
What do you think?