Hair Loss & Scratching

Question
Hi!
We have been to Angell Medical hospital in Boston twice with our little Cookie (4 years) and now fear Sammy Hoppertons (3 years) has same problem.

Problem: Cookie scratches a lot in her cage.  She has lost all her hair on her belly, hind legs, and backside.  Sometimes she has sores on her legs and chest.  Doc has done many tests but nothing shows.  Her personality has not changed but she is losing weight.  
Just today, Cookie's cage mate, Sammy Hoppertons, has begun itching and scratching his paws and legs.  
They seem to be happy piggies but I am worried for them.  
I have tried:
*many forms of bedding (no change)
*bathing (better for Cookie, her skin is not so flakey)
*thinking timothy hay problem switched brands (no change)
Could they have allergies? The only time the pigs does not itch is when cuddling with me.
Any advice would be great!! Thank you!

Answer
Has the vet treated for mites even if they did not come up on his exams. Mites are very common, and this really sounds like the case. I have information and treatment on mites on my website http://woopets.bravehost.com , on the guinea pig information page. Very rarely do guinea pigs have food allergies, as long as they are getting a normal guinea pig pellet, hay and fruits and veggies they should be fine. Guinea pigs can get ringworm, but it usually only results in hairloss, not flaking. I would however treat for mites, which can be done by your vet or by yourself. Let me know if you have any more questions.
Brittany