Just to update you all... As predicted my son bawled his eyes out well into the night. We are planting a pot of Basil over Basil's grave.
Bolt perked up a bit - he can hop around OK now although was very wobbly at first. But he's not eating much at all. Today all he's had is a few carrot shavings, a small amount of hay, nibbled a bit of grass and literally a couple of pellets - looks like he is having trouble pooing too - he won't go at all in his cage and waits til you put him outside but then he's straining like mad and grunting. He hates being inside and only perks up when I put him on the grass for a bit. But he looks so sad.
Any more advice - does he need to go back to vets? What foods should I try him with - apart from nibbling the grass, he will only eat when I put it right under him. He is drinking plenty tho - again only when I offer it.
Thanks for you help everyone.