Conditions Shelia is losing fur! = (

I would take her to the vet just to be on the safe side but look for a vet not associated with the humane society you got her from. You should get an objective opinion. The brown gunk sounds like it might be dried blood from where she tried to scratch that area. Missing fur is an indication of possible mites. They looked for mites and didn't find any but that doesn't mean they aren't there. Another reason to take her to the vet is that he/she might find some other underlying conditions that were not readily obvious to the humane society.

It's possible the missing fur may have come from a run in with another piggie but it's better to err on the side of caution and get her checked out to make sure she has a clean bill of health.

Is it the grease gland that you may be seeing? Here's a link if that helps: https://www.guinealynx.info/grooming.html#grease_gland

Better be safe then sorry is my motto!
I always like to take new pets to the vets when I first get them .. just so the Vet knows the animal, so if theres ever an emergency, You'll feel a lot safer and well looked after.
Hopefully there will be nothing wrong, and you'll have peace of mind knowing the pigs have had a general checkup
How are the pigs settling in?
xx Wonder xx

AnmlLvr14: I don't believe it's the grease gland because it's more on the back than by the tail and it lookes a bit different. Thanks though. = )

CavyMama: Thanks for all the info - I'm definatly taking them both to the vet!

Wonderwhiskers: Good Motto...the pigs are doing fine, but, as expected, they run into their pigloo when I come within a 10 mile radius of them = ) I'll post pics as soon as my camera starts connecting to the computer right... (Grrr!)

Glad there well!
Aww don't worry about them running away, they'll get used you to you soon enough
hehe as soon as they realise ..mummy=veggies!

Mummy DOES equal veggies, but try telling MY pigs that!