I think that Steve is probably spot on. First time round you drained the infection, now with reduced inflamation you've been able to remove the source of the infections.

What are people's thoughts on the bone/splinter? My concern right now would be that it's a bone which has perforated the intestine and worked it's way out, although with a wild snake it's probably more likely to have been a penetrating injury - so an embedded splinter that then got infected.