Unfortunately the vet didn't give any gut support -- I'll be requesting some if needed. So far poos and wees are still fine, but I think this might reflect gut activity just before the attack so I'm still watching out. There are some tiny baby poos in the cage too, which may also be him -- he's still doing regular adult poos too.
I'm getting a minimum of 40ml CC into him, but usually around 55ml. He's so annoyed with me feeding him he's nipping me, which is the first time ever! Sorry little chap. He lost around 20g between yesterday morning and this morning, but that's the difference of a full bladder so I'm not hugely fussed. I've been giving him some Loxicom and it appears to be masking any pain, which is good.
He's still not a fan of moving, and his feet are getting quite red -- I wouldn't be surprised if he gets bumblefoot again, so may be doing Epsom salt baths tonight.
Finally, the thing I'm most worried about... Both of his eyes have been quite sunken in, especially the one with a bite right above it. I've been very vigilant about making sure he's hydrated (with Dioralyte), and the one which isn't injured looks normal-ish again but the other one is very sunken (no photo yet I'm afraid). Even worse, his eyes keep vibrating inwards -- the only way I can describe this is the opposite of a rat boggling, the eyes don't bulge outwards they withdraw inwards and I can see the mucous membranes. I've heard this can happen when a guinea pig is ill, but it's very distressing to watch.
I'm planning on getting another vet appointment maybe for this Wednesday, unless anyone thinks I should be going in earlier re: the eyes?