The vet just rang with the results of Gus's blood that he took on Friday and to our relief everything is back within normal range again.
So now he just needs a bit more time to build himself up again and then Gus will be back out having fun too!
Its seeming like all his problems are related to his fall back at the end of August. We had another vet out this time and while he said the results Gus had the first time around could indicate a kidney problem those same results could also be linked to muscle bruising etc.
Anyway he's on the way back up and thats what counts.