Guinea pigs don't have fleas. Please have her checked by a vet for mange mites. It can be that she is just being very uncomfy with being handled, but you want to eliminate the parasite angle first. Please do not home treat on spec with cheap shop products, as they are too low dosed for an effective treatment; always see a piggy savvy vet for a proper diagnosis.
The parasites that guinea pigs can have:
- mange mites (trixacarus caviae): invisible to the eye, lays eggs in skin, very painful and can kill if untreated. Can cause fitting in advanced stages.
- fur or hay mites, also known as static lice (chirodiscoides caviae): mites are near invisible, but the brownish egg cases on hair at the bum end are what you usually see (like somebody has used a pepper mill over the bum end of a piggy), comparatively harmless, come with the hay typically in autumn.
- running lice: usually white or yellow small blood sucking moving bugs in the fur
It is important that a vet checks whether he is dealing with parasites or a fungal issue. They can look much more similar than show pictures suggest.
https://www.theguineapigforum.co.uk/pages/guinea-pig-vet-locator/
If you can, please lift your new girls out in a walk-in cardboard box, in which you place some soft hay to lure her in. This is going to take a lot of the stress out of the picking up process.
https://www.theguineapigforum.co.uk...stincts-and-speak-piggy-body-language.117031/
