Just heard from mum - Tobz is a lot better today thank goodness!
Mum took him to the vet this morning, who gave him a good look over. Turns out the main pad on his hind foot was very bruised and tender, though there seemed to be no obvious damage. He's had a shot of antibiotics and a shot of anti-inflamatories and he's going back tomorrow for a follow-up.
Tobz has been walking around a little bit this afternoon, albeit rather stiffly, and managing to put weight on his poorly foot. The boy has got his appetite back which is good news, as all he ate yesterday was a Cat's Delight treat stick. He's now currently curled up on his sofa sleeping the meds off. Of course, will keep y'all posted as and when I get further updates from mum.
It's a major relief that it seems to be nothing more than a bad bruising, though obviously, we'll see how things go. As to how it happened, it's anybody's guess...
Thanks to everyone who's been sending him their wishes!