Hi all, in response to everybody replying to this post; I have just re examined him in an attempt to take a photograph and have just realised that there is outward swelling. I can only imagine that this means the injury is fairly recent, as I definitely would have noticed. He's become quite irritated and the only thing he wants to do is hide, however, I managed to take a poor quality photograph in which the lump is just about visible (albeit at an odd angle). The lump is further down than I thought, and what is not apparent in the photograph is that it's rectangular in shape. I don't want to go prodding him any further tonight because he's so agitated.
The first is a picture of Pretzel from earlier today, in which I don't think the swelling was visible, the second is where you can sort of see it.
His viv looks sort of bare & sad, but I removed as much as I could from his it so I could get a picture without having to handle him physically.
Edit: & For those asking he's a normal BP.