"They were only little dots on his arm," Mrs Crimp said.
Staff removed Elliott's pyjamas and he was covered in a rash.
"All his limbs were covered with it ... It was a deep red and then a deep purple."
Elliott was suddenly surrounded by several doctors wearing gowns and gloves.
"I knew it was bad ... The scary thing is it's just so fast."
He was rushed to intensive care and Mrs Crimp called her sister, who is a doctor, who told her how serious Elliott's illness was and that he could die. The young boy was put in an induced coma and flown to the Starship. He remained in an induced coma for several days while fluids were pumped into his body to improve his blood supply.
Mrs Crimp said doctors told her Elliott had a deadly disease which was super-fast-acting and she was lucky she had brought him to hospital when she did.
She was relieved Elliott developed the rash while he was in Rotorua Hospital as she might not have realised what was wrong if he had been discharged and got the rash later.
During his initial days in hospital, Elliott's left lung collapsed. That has since improved.
Elliott was constantly monitored by staff. Mrs Crimp was by his side all day, while her husband, James, sat with him all night for two weeks.
Mr Crimp works in the mines in Australia and he flew back to New Zealand the day after Elliott was admitted to hospital but could stay for only two weeks. He works in Australia for four weeks and then returns to New Zealand for a week.
Mrs Crimp said she spent hours just staring at her son while he was in a coma. It was horrible looking at what was happening to him but she knew he was in good care.
"I never felt scared, with how they worked on him. [The staff] have been amazing and professional."
Mrs Crimp cried as she spoke yesterday of her son's ordeal but said she had managed to keep her emotions in check for Elliott and her two other sons Ian, 6, and Angus, 5, who are moving to Auckland to stay with her at Ronald McDonald House.
She said what her son had been through was definitely the worst thing she'd had to deal with but it had made her stronger to face the future for her son.
Elliott is likely to be in the Starship for a few months but it was hoped he would be home by his fourth birthday in January.
Some of his fingers and toes have gone black and he is expected to lose part of two fingers and the tip of another. He could also lose the toes on one of his feet.
"The whole way through I could see the fingers and toes. I've just accepted it. He has all the major stuff he needs. I'm happy that I've got my kid."
He is also likely to need skin grafts. Every time he bends his knees they crack and bleed.
Mrs Crimp said she had tried to talk to Elliott about what had happened but he did not want to talk about it.
"He is going to have to learn to walk. It looks like he is going to lose his toes on his foot and he will have balance problems ... It's going to be life-changing for our family."