Charlotte Caldwell has campaigned and raised funds for her five-year-old son, Billy, who has severe epilepsy.
When he was just six-months-old, Ms Caldwell was told by a doctor at the Royal Belfast Hospital for Sick Children that he would not survive.
She refused to give up hope and took him to Chicago for life-saving treatment.
She raised hundreds of thousands of pounds and when the money ran out, she asked Health Minister Michael McGimpsey to fund similar care at a private facility in Oxford.
They left Chicago but when they got to Oxford, the minister appeared to do a U-turn and the funding stopped.
While Ms Caldwell challenged the turnaround, she borrowed Â£30,000 from the bank and from family members to continue the treatment.
Now the Department has changed its mind again and has agreed to send Billy back to Oxford.
Ms Caldwell feels the minister should refund the money already spent.
"I feel that he has a responsibility to Billy, and at least let us be able to pay back to the bank and to my family the money that was borrowed," she said.
Deputy First Minister Martin McGuinness has supported the family.
"I would hope that both he and others who will be responding to this request will be compassionate and will recognise that this family has been through a very difficult ordeal over many years," he said.
"The reality is that the child has recorded enormous progress."
Mr McGimpsey declined to be interviewed, saying he could not comment on patient care plans because of confidentiality.
Ms Caldwell said: "I'm completely puzzled and bewildered why we have had to go through this because it's Billy's life at the end of the day and we're just trying to give him the best possible start in life."

A gothic horror novel, a Victorian murder mystery and a biography of the creator of modern environmentalism were also category winners.
The overall Costa book of the year will be revealed on 26 January.
Atkinson won the top prize in 1995 with Behind the Scenes at the Museum.
Other category winners include former teacher and librarian, Andrew Michael Hurley, who has won the first novel award for his debut, The Loney.
The gothic horror initially had a first print run of just 300 copies. The judges called it "as close to the perfect first novel as you can get".
Scottish poet Don Paterson won the poetry category for a second time for his "tour de force" collection titled 40 Sonnets. He last won the award 12 years ago.
Historian and writer Andrea Wulf won the biography award for The Invention of Nature: The Adventures of Alexander Von Humboldt, The Lost Hero of Science.
She tells the story of the visionary German naturalist whose ideas changed the way we see the natural world and created modern environmentalism.
Young adult fiction and children's writer Frances Hardinge won the children's book award with The Lie Tree, a Victorian murder mystery.
The five Costa book award winners each win Â£5,000 and are all now in the running to win the Costa book of the year.
It is the only major UK book prize that is open solely to authors resident in the UK.
Last year's Costa book of the year went to Helen Macdonald's H is for Hawk. In 2013 it was The Shock of the Fall by Nathan Filer and in 2012 it was Bring Up the Bodies by Hilary Mantel.
The mother of a Castlederg boy is asking the Department of Health to refund money she spent funding his health care in England.
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Kate Atkinson has won the Costa novel award for the second time in three years for A God in Ruins - the companion novel to Life After Life, which won the award in 2013.