Thank you RU'ers for your thoughts and support above.
U/D - have just got back from the vet and here is where we are at with Lillian. The vet performed the procedure to massage Lillians tummy to see if she would pee- which she did on command. Loads! The vet said that all she seems to have had today is bunnies with UTI's - which is I think an unusual situation and one which my wife and I discussed in the car on the way home. That said, at least Lillian isn't in that sense, an unusual case.
However, yes, where was I? Oh yes, Lillian happily filled the examination table with her finest pee - which on the face of it, didn't seem to be tainted (not that one can tell on a black table). But last time (ie 4 weeks ago) you could see the pee was quite sandy in consistency and today it seemed to be nice and watery.
The vet was puzzled although we explained our concerns and recent minor behaviour infractions and the vet suggested that we do a colopscomy or something like that.
But not today - thankfully. Lillian had her temerpature taken - perfectly fine - no concerns. So that was quite reassuring because an infection could possibly raise temperature.
She broke the scaes at 3.5kg so she's in the mahoosive category. The vet said that physical examination of Lillian was positive and she presented as very good indeed. So that was a puzzle. One thing additional was that as I picked Lillian up to put her in the carrier before we went to the vet, I noticed a wound on Lillians upper back - about the size of a 5p piece that was scabbed but sub-surface so some varmit has had a piece of her and I know it wasn't Henry. We showed this to the vet (god, I feel such a bad bun dad not noticing this), and the vet said the wound was not infected and probably a few days old.
So, generally, Lillian is presenting as fine - which gives the vet a dilema, but we have booked her in on tuesday with the exotic rabbit mad specialist who treated Henry at the start of the year, and she will perform this colopthingymajig - which seems to involve inserting a catheter and taking urine fresh from the bladder which will give the best indication of any underlying infection - if indeed there is one. So Lillian will spend half a day in the hospital and we should know whether there is any bugs there, and if so, what would be the best abx to tackle them. The vet didn't want to just use a general abx in case of making Lillian resistant to abx so I agree with this line of treatment. It seems belt and braces but to be honest, it's reassuring to take that route so that Lillian is given the best chance of treatment. We're still puzzled if there is indeed anything wrong or if I'm just being a neurotic over sensitive over reactive silly billy who can't spot when their rabbit has been attacked by some varmit.
I'll keep you all posted as to what, if anything, the vet finds on Tuesday.
Thank you all again
Craig xx