scab on guinea

Question
Hi, I bought an 8 month old female guinea nearly a week ago and she is now living with my 2 other females who are both about 1 1/2. They all seem to be getting on ok but I have noticed quite a big scab on the new guineas back.  I have checked for signs of mites or lice and cant see anything but I have got shampoo that I used when the other 2 had lice before. Should I wash her with this in case? And is it likely that one of the others has done this 2 her? She is still quite nervous when we try to get her out of the cage but doesn't seem afraid of the other guineas? thanks.

Answer
Hiya Charlie
it wont hurt to wash her in the shampoo,and keep an eye on them all for fights breaking out.
There will be a bit of squabbling over who is in charge but only intervene of your little one is in trouble and getting really picked on.
Get back to me if you have more concerns xx