Infection Our guinea pig got dry skin, loss of hair and looks like dried blood

It looks like a fungal infection to me, read this page for more information about fungal infections https://www.guinealynx.info/fungus.html

Also it is important to know, often when you take a pig back to the store that it was bought at for medical care they will take the pig back and keep it for several weeks as it is treated even if the treatment is something you could administer yourself at home. I know several new owners have been very distressed at the prospect of not being able to see their pig for several weeks, also being away from his cage mate for that length of time would mean you would need to introduce them as if they had never met each other before.

ETA: Also as you got them from a pet store it would be a good idea to double check that they are the same gender, it is fairly common for pet store pigs to be missexed. Here is a great page with images to compare your guinea pigs to https://www.cavyspirit.com/sexing.htm

Thank you so much. Do we need to take him to the emergency right now?

No, fungal infections are not life threatening unless you leave them long enough to spread over most of the body. Some people even opt to treat at home with creams available from a human pharmacy, but in your case it is very close to the eye and there is an open sore on the lesion so you would probably be better off seeing a vet for an oral treatment.

Do be cautious though, fungal infections are contagious to humans (athletes foot is an example of a type of fungal infection common in humans) so wash your hands after handling him. How likely you are to catch it depends on your immune system.

Ditto Soecara, especially on turning them over and comparing the private parts. Pet stores are notorious for mis-sexing guinea pigs.

Also, for the next time he needs to see a vet, go ahead and find yourself an exotic vet in your area. Most vets get little to no education and training in care of exotic pets, and usually cannot treat them safely.

Thank you all again, we have scheduled an appointment for House tomorrow. My girlfriend doesn't think it's a good idea to use any cream before we see the vet, do you guys agree?

No, we don't agree, or we wouldn't have recommended the treatments that we did. If it were me, I'd treat them (the treatment advice comes from Guinea Lynx, the premier site for guinea pig medical information on the internet), and save the vet money for a serious illness.

Fungus can be treated by yourself without a vet visit, although it being so close to the eye might be a slight worry. If it makes you feel less anxious you can of course take him to a vet. Just make sure the vet is an exotic vet whose experienced with guinea pigs. Normal cat and dog vets do not have the training and even some exotic vets lack experience.

While I do understand your girlfriends concern, Guinea Lynx is a well respected, trusted website and I hope both of you will come to see it as such. I'd suggest reading both the care and medical guides on there.

Here is some advice on how to find a good vet:

https://www.guinealynx.info/vet.html

In this case I personally would wait until you can see the vet tomorrow before starting treatment if you do want to go for an oral treatment, which as I said before oral would be ideal in this situation considering the hair loss goes all the way to the edge of the eye and for effective treatment using a topical cream you need to cover the whole area of hair loss. I have treated at home before with a topical cream without seeing a vet but that was because treating topically was the most ideal treatment for my situation.

If you were to start treating now with a cream but still want to go to the vet for an oral treatment, you would have to be extremely careful not to get any into the eye, possibly even consider only covering the worse bits and avoid getting too close to the eye, and as always when using a topical cream use it sparingly and rub it in well with a q-tip, you don't want him to be able to rub any off an ingest it. There is also the possibility that starting treatment now could affect the results of any tests the vet wants to run so of course you would need to tell the vet that you already started treating and exactly what it was you started treating with (consider taking the tube of cream with you), but this case looks like a very standard case of fungus so an experienced vet would likely treat anyway. It would be a good idea to also take the picture you posted here to show what it looked like before you started treating.

Thank you guys, we did end up going to the exotic vet (who luckily had a great about of experience with guineas) having both of our boys checked and it was confirmed that at least one of them had ringworm. They are both now in the different cage, our room got disinfected and they are taking oral medication. I'll post more pictures as it goes on.