I phoned back again later and although his temperature had gone down, I knew he wasn't right so they said to go in. When the doctor saw him, he said that he thought Xander might have another urine infection (he'd had one at about six weeks old) and to go along to the Assessment Unit to get it checked out.
We got to the CAU and went in to get him weighed and a urine sample...as we stripped him off, I noticed that a rash has come up on the back of his hand and that his fontanelle (soft spot on top of head) was like bubble wrap.
It was all a rush from there...they whisked him into a room, stuck drips and various other stuff on/in him. They treated for meningococcal septicaemia. It turned out to be Y strain (have no idea how he got this particular strain). All went well for first few days, he then started to 'fit', and then gradually his veins started to give up (feet, ankles, arms, wrists, groin) and he was left with drips in his head (not sure why but I found this the most distressing).
He was in for a total of three and a half weeks, had three lumbar punctures, two EEG's, one MMR and seems to have made a full recovery (albeit he is only seven months now). I count my blessings every day that it was caught early on and am thankful that the hospital staff were so amazing.