Scab on piggy's face? Dried blood, mites, or other?

[dchen298]

This morning I went downstairs to give my pigs their morning veggies and I noticed a strange black spot on one of their faces, right inbetween his nose and mouth. This is a photo from this morning:
Here is another closeup from when I took him out for floor time
I took him out of his cage and tried to get a closer look at it, and it seemed like it may have been dried blood, possibly from a scab? My initial thinking is maybe he got into a tussle with his cagemate. However, upon googling about scabs and guinea pigs, a lot of results about mites and ringworm came up too.
It's important to note that this was not there yesterday. Luckily, I take pictures of my piggies every day so here's a comparison photo from the day before
So what do you guys think this is? Is this dried blood, or is it a case of something more serious? Should I schedule an appointment with his vet? Any help would be greatly appreciated; thanks!

[Lynx]

It sounds like a tussle/bite is the most likely cause. If he is cooperative, you could try soaking off the scab and trying again to get a good look. Read over the method of getting liquid medication into a guinea pig (gently but firmly pinning the head so it doesn't move) after it is cleaned off to get a better look. A good description on that page:
https://www.guinealynx.info/tips.html#oral

If you can get a good closeup with a camera, it can often be blown up to show you what is going on.