The active 20-year-old suffered from severe back pain for three days before waking up one morning to discover his legs had stopped working.
He was diagnosed with a rare spinal infection after doctors discovered an abscess had burst between his shoulder blades.
Callum, who lives in Yeadon, is hoping to raise thousands of pounds to fund equipment to help him get back on his feet and compete in the Paralympic Games in Brazil.
He said: “I thought I had back pain so I got my mum and dad to bring me back home to Leeds from university in Northumbria.
“I woke up in the morning and my legs just stopped working.
“It was the probably the scariest thing to happen in my life.
“They called an ambulance and I was just screaming in agony.
“I was told that I paralysed and that I had only hours to live and needed a life saving operation.
“It was over-whelming and all at once so I was really shocked more than anything.”
Callum spent hours in surgery at Leeds General Infirmary following the devastating diagnosis in September last year.
The student, who worked part time at The Station pub in Guiseley, spent months in hospital before he was allowed to return back to his Leeds home last week.
He said: “24 hours earlier I was a happy-go-lucky student and then I was paralysed just like that.
“I hadn’t done anything wrong.
“There is a one in 50,000 chance of getting it.”
Doctors believe that the abscess could have developed after Callum stood on a sea urchin in Greece.
His friends, family and former work colleagues are now rallying around to raise thousands of pounds to pay for his physiotherapy and equipment to help Callum walk.
He added: “The support has been amazing.
“From being in a hospital I realised that there are two things you can do.
“You can be depressed and you don’t get anywhere or you can just be focused and get on and just do it. I am just glad to be alive.”
To find out more about Callum’s fundraising visit www.callumhalltrust.com.