Guinea-pig allergy

Question
Hello,
my guinea-pig has the following symptoms:
itchy bald patches
occaisional open wounds from scratching
other than that she is in perfect health
i've been to three vets and she's been diagnosed with mites and other forms of parasite which she has been medicated for but to no avail.
the last veet i went to said she may have a food allergy.
can guinea-pigs be allergic to certain foods?
i don't feed her anything weird and her hutch is always clean, do you have any advice?
ps: she only gets itchy around winter or in a humid summer.

Answer
Have any of the vets given her a shot of Ivermectin for the mites? Only ivermectin will cure mites and she really does sound like she has mites. She also might need 2 shots of ivermectin about 14 days apart to get rid of all of them. Rarely do guinea pigs have food allergies, I have never heard of a case at all. Hairloss can be hormonal sometimes for females, but I would call your vet and ask if she had ivermectin to treat her mites, if not then that is what she needs, I could even give you the dosage if your vet needed it. Pigs with mites usually are affected by the weather also, I know I had one case a while back with a male pig that would like fine for about 3 months then all of a sudden start scratching and loosing hair again, he only changed during the winter and humid months too, but with ivermectin he got better. Let me know if you have any more questions.
Brittany