crusty skin cavy

Question
Hi.  My male guinea pig is 3 or 4.  A few months ago he started to develop crusty, bumpy and scaly patches on his skin.  It healed but now it's spread to his whole body except his face and he broke the skin in one spot by scratching probably.  I also noticed he had a few "seizures" last weak twisting his body, mouth open like in pain and eyes looked fixed. He also looks more sleepy and his eyes look sick.  But he eats normally and squeals for food.  I feel bad because I don't want to pet him anymore he feels too yucky.  Is there a treatment that I could do at home without a vet visit?  Is it mites? Do you think he'll ever be better since he's getting old?  Do you think it's contagious because we just got a rabbit and they shared the same cage for 2 days before I thought it might be. Thank you.  

Answer
Hello it sounds like your guinea pig has mange mites. They can spread and the only treatment is to give a dose of Ivermectin. You can get Ivermectin over the counter for horses, but you need to talk to a vet about how much you need to give your guinea pig and how often. Ivermectin is the only thing that cures mange mites. The mange mites live under the skin and cause itching and flakey skin along with severe pain for the pet. If you don't treat him for the mange mites he won't get better i'm afraid. :(