Mum Emily McLeod is desperate for answers.
Four months ago her beautiful boy Christian Bailey, whom she shares with her former husband Jamye, was hospitalised after experiencing severe developmental regression. In just 24 hours he lost the ability to walk, talk and swallow.
And doctors have no idea why.
"It was overnight," Ms McLeod of Baldivis, Western Australia, tells Essential Baby, explaining that the loss of her six-year-old's communication skills has been particularly "drastic".
"We have no idea what's going on in his head," she says. "We get a word here and there that just looks he's trying to make noise. That's the hard thing. Trying to guess what's causing the issue."
And, with limited ability to communicate, Christian's worried family have no way to tell if he is in pain.
Christian, who was previously diagnosed with autism, global developmental delay, and epilepsy, was admitted to Perth Children's hospital in September. Since then, his symptoms have included severe muscle twitching, some involuntary movements and more severe seizures. He has also become increasingly rigid and agitated. Without medication, Ms McLeod says he has "all over body twitches," which they believe might be causing him pain. There have also been episodes where Christian's eyes shake from side to side, a symptom that lasted around three weeks.
"Christian's agitation has become so bad he is unable to sleep more than a couple of hours a day and even then he is very unsettled," Ms McLeod wrote in a Facebook update on Friday, adding that he now requires all feeds and fluids by nasogastric tube (NGT), constant use of a wheelchair and still has very limited interest in interacting with anyone.
His grandmother, Kate Bailey, says the difference is "horrendous". "In the last 4 months Christo has changed from a happy Paw Patrol loving young boy, to a child who can't do anything."
But medical professionals are stumped. Despite undergoing "every test his specialists can think of", including CT, MRI, EEG, EMG, biopsies, Whole Exome Sequencing, lumbar puncture, nerve conduction, and full blood count, they're still no closer to a diagnosis.
Christian with his dad Jayme before his sudden illness. Photo:Supplied
According to Ms McLeod, diagnosis has been made more challenging because on paper, her son is "medically healthy", with no tests indicating that further investigation is warranted. In addition, Christian's symptoms have been constantly changing making it even more difficult to reach a consensus about what's going on.
And while the rare neurological disorder Rett Syndrome which occurs almost exclusively in girls was initially suspected, this has now been ruled out.
"We find ourselves begging for something to be there ... so that we at least have some direction," Ms McLeod says. While doctors agree that the little boy is likely to have a rare genetic disease of some kind, Ms McLeod says their opinions around his prognosis vary, " from expecting things to improve on their own to this being a regressive and life-limiting condition."
With no leads, the specialist hospitals the family have been in contact with overseas have also, as yet, been unable to help.
The family are now issuing a global plea for help, asking for those who might have encountered something or have expertise in the area to contact them.
"We are desperate for any assistance finding any medical professionals (world-wide) that can help us figure out what's happening and ideally treat the condition," Ms McLeod says, adding that they've already received messages from people with suggestions of possible conditions to explore and specialist recommendations
"We'd love him to be able to develop typically," Ms McLeod says, "but even just getting him back to his happy self where he's got a good quality of life. He was always laughing - he found everything amusing. It's nice when we get small glimpse of his smile here and there."
And while those small glimpses of their little one are rare, they're also a glimmer of hope.
"Seeing that pushes us more to help him because if he's in there he'll be going through hell not knowing what is going on."
You can contact the family via Facebook here