What is this sore my guinea pig has?

[KatHarvey]

Hello I am new to the site!

I have two young guinea pigs (5 months old) that I got from two different breeders. I got Harvey in August and Teddy in October.

I notice Harvey has been scratching a little more lately, so I search through his fur and find this! A sore on his butt around the size of a dime!
I frantically looked for any more sores and there were none, every other part of his skin is perfect, not even red.
I then frantically searched Teddy (his roommate) and his skin is perfect.

No matter what it is, I am going to the vet today. From my diagnosis I think it’s mites? Tell me what you think.

But my main question is if it is mites how did this happen? Is it my fault? My guinea pigs mean the world to me and I think I take excellent care of them, so why would they mites?

 

[Claire W]

Sadly that does look like mites although only the vet will be able to diagnose so it's a good job you're taking him.

Please don't blame.yourself. Depending on what mite it is, they can come in on the hay or sometimes they just happen. They can just lay dorment and then suddenly become active. It's nothing you have done