"We've had days where he is running around in circles, just an absolute box of birds, like a normal toddler doing normal toddler things.
"To other days where he's completely catatonic and he is on an oxygen mask, he won't move, he won't wake up — really scary days to be honest."
Jody said the treatment was going to plan so far and recently Grayson had been allowed short breaks off the ward.
If she had a Christmas wish, it would be that the treatment continues to work.
"Sometimes you think if I had it any other way would I want anything different for him today? Everybody wants healthy kids and happy kids, and 99 per cent of the time at the moment he is happy, and apart from the healthy - we're working on it."