Update on Smudge:
Her little foot is beginning to go down massively, there's still rather a lot of swelling but it's not nowhere near as bad as it was! The only thing that's holding us back at the moment is the scab on the bottom of her foot. She's still accidentally catching it on occasion and making it bleed, but in also thinking of starting up the salt baths again in order to help the scab come off. Once the scab comes off, I'm happy to re-introduce all of the girls and hopefully, with luck, get them all back in together happily!
She's still using the foot really well - popcorning very high for treats - despite some of my so called "friends" saying really nasty stuff. Apparently because I can buy a New Guinea Pig for £20, I should put Smudge to sleep as she isn't worth the money. Gyah. Been heartbreaking hearing stuff like that - Smudge is a living being, and she's not suffering - while she's mad at me for not letting her run around and not with her friends currently, she's still happy. I'm confident that she'll heal up completely - maybe a slightly wonky foot; but she's using it perfectly so I have no concerns.
I've also managed to get hold of a very local vet practice with a particular vet who's had lots of experience with Guinea pigs in his years; they were really understanding and seemed lovely, so in the new year when Smudge needs a check up; I think I'm willing to swap all my records over to them or a hand-over.
Overall I'm so relieved that this is all turning out so well. I also got Smudge's foot cream in the post which in considering using anyway - to help keep that scab moist and prevent her from itching it off! But orverall Smudge is doing great, her appetite is fantastic and she's back to my old Smudgey again.