CHIHUAHUA HAVING AN ALLERGIC REACTION??

own a pure-breed Chihuahua, he's about 11 pounds but larger than most --- not just in weight. He's turning three in June.

We took him out to get his nails cut, which went fine. He's primarily an indoor dog. He takes walks about four times a week, and is up to date in heart worm & flea medications.

We (my family and I) bought him new Dentley's Rawhide Twists in small. He's never had them before.

First we noticed a small bump on his head. The bump grew and grew and grew to about the size of a quarter when suddenly a ton of more little bumps developed. Eventually, it got to the point where his eyes were nearly swollen shut.

Before you ask me why I'm writing this instead of taking him to the vet, I've already given him benadryl according to his size and his breathing is fine as well as his heart rate.

The bumps seem to not bother him besides itchiness. His tail was still wagging! I put a cold wash cloth on him and it helped, I think. They're slowly going away now but probably from the benadryl. We've located a pin-point on the first bump that appears to possibly be the origin of a bug bite? You know how when you're stung you can tell exactly where?

What do you think is going on? I think its either a reaction to the rawhides or a bug bite.