I know this is a year and a half plus but I have the answer now.
It was basically issues with her bowel. It lead to her being hopitalised shortly after this original post where she was in hospital for about 10 weeks.
Her bowel (neuropathy) wasnt processing the food properly so because of this - she wasn't erm depositing well enough in the toilet so the smell was coming from the rotting in her bowl of the food hence the smell coming from her pores.
I would advise anyone to get this checked up on because I'm annoyed at our doctors (again!) as when we mentioned this they didnt say "Oh yes..maybe its this..."
She is at about 85% now but can't have fruit, veg or fibre as her bowel still has issues with it and she probably only goes the bathroom 2 or 3 times a week