Ok so Jane spoke to the vet and this is what he said........
"He says it sounds as though Milly was harbouring some sort of infection before he had his vaccination. The vaccination then caused an onslaught on his immune system. Mike said if the Vaccine had been the primary cause of death then Milly would have passed away within 48 hours. The fact that he got better for a while makes Mike think Milly had some sort of bacterial condition going on which, eventually, his immune system could not get on top of. Mike said that he did not think Milly died from VHD as the symptoms dont really fit, except for the high temperature. Although he said without a Post Mortem its impossible to say for sure. He said the most likely cause of death was an acute bacterial infection that his immune system could not cope with. He said Milly may have been born with an auto-immune deficiency. So he could not cope with acute infection or vaccination. "
I have now at least some closure, but I also have a huge amount of guilt. Could I have done anymore........or somehow treated this possible bacterial condition he may of been suffering from.......
Jane, thank you for contacting the vet for me.