That night, last Thursday, a doctor suspected tetanus, which fitted with the fact Alijah had a cut on his foot, but more importantly he had never been immunised.
Alijah was admitted to a ward but 24 hours later he was moved to intensive care, put into an induced coma and paralysed by drugs to prevent the spasms and relieve the pain.
His breathing had to be monitored because the muscle contractions could close the airway, and later a tracheotomy tube was inserted in Alijah's throat to help him breathe.
"That is really scary as a parent to watch your child like that," Mrs Williams said.
Slowly over the next few days, Alijah improved. He is no longer paralysed, but can communicate only by nodding or shaking his head.
Yesterday, he smiled for the first time when cousins gave him their drawings.
Mrs Williams said she had not stopped crying since her son got sick but she was hoping for a full recovery.
"He's getting better and better. He's still getting the spasms but they're not as often or as long."
Doctors have told the couple, who have two other children, Emias, 9, and Jaiya, 2, the recovery could be long.
Alijah could be in intensive care for six weeks, in hospital for four months and face a year long recovery.
Mr Williams said the disease was devastating and the family were "absolutely shocked" by it.
The couple wanted to warn other parents of the dangers of tetanus.
Mrs Williams said they made what they thought was an informed decision not to vaccinate any of their children because of concerns over adverse reactions, but had since changed their minds.
"Our two other children were immunised last Friday."
They wrote to Alijah's teachers at his school urging parents to consider vaccinating their children, at least against tetanus and whooping cough.
"We're doing this only to prevent any other kids and parents going through what we have gone through."
The clinical director of the Starship's emergency department, Dr Mike Shepherd, said tetanus was an incredibly painful and debilitating condition which took months of recovery.
"People used to die of it a lot. If you don't immunise against it, then it's definitely a risk."
Tetanus was caused by a poisonous toxin produced in bacteria found in soil and harboured by animals.
It could be caught only through a wound but that could be as insignificant as a cut from a rose thorn.
Dr Shepherd said there had been at least five cases of tetanus in unimmunised children at the Starship in the past 10 years.
The director of Auckland University's immunisation advisory centre, Dr Nikki Turner, said 10 per cent of tetanus cases were fatal.
"Patients often end up in intensive care and they need to be on a ventilator because they go into paralysis and can't breathe. It's a very nasty, very painful disease.
People often did not realise the seriousness of the disease and made their own assumptions about vaccines from reading incorrect information on the internet, she said.
"We hear stories from parents who say 'I wouldn't have taken the internet story so seriously if I'd known'."
Q&A
What is tetanus? Tetanus toxin is one of the most potent known poisons and contracting it does not build immunity. Symptoms include fever, hand and foot spasms, drooling, difficulty swallowing, lockjaw, and powerful muscle contractions which can cause fractures and muscle tears.
How bad is it? Despite modern intensive care, 10 per cent of people who get tetanus die. Those who survive usually make a full recovery after physical rehabilitation.
How can you protect yourself? NZ has had vaccinations since 1960. Almost 95 per cent of infants and children are vaccinated against tetanus, diphtheria and pertussis (whooping cough) at 6 weeks, 3 months, 5 months, 15 months, 4 years and 11 years. After that, a booster is recommended every 10 years.
Source: Immunisation Advisory Centre.
