Allergies How Can You Tell If Your Guinea Pig Has Allergies?

[CC Cookie Dough]

Lately I have been wondering how to tell if my guinea pig has allergies. About a month ago, I noticed that my guinea pig was sneezing a lot, scratching herself, and rubbing her nose. I thought that this might be caused by a URI and by mites or fungus. My guinea pig lost the hair on one of her ears and the skin looked very scaly. I immediately took her to the vet to get her checked out, and they thought that she probably had mites and that she could have a URI. I was given two types of medication, which I gave to her as I was supposed to and I cleaned out her cage every other day to keep the mites away.

The ear now looks perfectly healthy (the hair is still gone, but that will take a while to grow back). However, I have still noticed her sneezing a lot. One time I was shocked to see her sneeze a white mucus blob onto her nose. I called the vet again and since Cookie Dough has been very active (even at the beginning of her symptoms from a month ago) and took all of her medicine, the vet was reluctant to prescribe her more medications unless she got worse. Cookie Dough is still very active and eats and drinks normally. I have not seen mucus since.

What worries me is that she is still sneezing frequently (one of my theories is that it could be from hay dust), still rubbing her nose, and she is still scratching herself a lot as if she is really itchy. Nothing looks visually wrong with her. So that got me thinking: is it possible that she has allergies of some kind? If she did have allergies, how could I tell? I have seen people suggest going to the vet, but I am confused as to how the vet could figure out if she had allergies. I am also wondering: what kinds of things could guinea pigs be allergic to?