parasitic infestation?

Question
My guinea pig has this white scab looking thing growing on his right ear. We also found something similar but smaller to that on his right side near his arm. He has had hair loss in these places, and itches them constantly.  I looked back at them the next day, and it looks like the one close to his arm has gotten bigger. We were guessing that it was a parasitic infestation, but we have never had a guinea pig and don't know anything about sicknesses they can get. When I bathed him, I had forgotten about them. When I was done, he was itching himself even more. I was wondering if you could tell me a little bit about what parasitic infestations look like, and how to get rid of them. If not a parasitic infestation, what else do you think it could be?

Answer
Ivy,

When I see an itchy Guinea Pig, I think of 2 things.  Dermatophytosis (ringworm) or mites.  These are treated very, very differently.  Bathing him will usually not help, and can make things worse in the case of ringworm.

The best thing you can do is find a veterinarian who sees exotic pets and take him there to be diagnosed and treated.  Whether it is mites, ringworm, or something else entirely, a veterinarian should be able to figure out what is going on and treat accordingly.

Good Luck to you.