An MRI eventually revealed every parent's worst nightmare, a tumour growing on her frontal lobe and a cyst on her temporal lobe.
"I just felt ill," Robertson said.
"I thought why an innocent 7-year-old?
"You can empathise with other parents whose children have been through something but until you hear it's your kid, it's something you don't [understand]."
The neurologists believe it is a slow-growing cancer but won't know until it has been removed and tested, with a surgery date yet to be set, Robertson said.
Robertson said the medication and tumour had taken its toll on Isla.
"She was the epitome of an energiser bunny but because of medication and the tumour the last six months have been hell.
"She's definitely not who she used to be."
In addition to the seizures, Isla has also developed sensory aversions to almost every piece of clothing she owns as well as food, bedding and everyday noises, Robertson said.
"These little everyday things can set her off and (it) is traumatic for both [of us]."
Later this year mother and daughter will travel to Starship Children's Hospital where Isla will undergo more extensive EEGs and testing before having her tumour removed.
Following this she will be off school for four weeks and be slowly reintroduced to school life.
A Givealittle page set up to help support Robertson, who is a single mum, has already raised more than $6000.
The money will go towards the cost of travel to Starship Hospital, psychological appointments, Olivia's time off work and Isla's rehabilitation after surgery.
Ashleigh Smith, the friend who set up the page, said Robertson struggled with asking for help.
She said she was immensely grateful for the support though, particularly to those at Te Mata School, which Isla attends.
"I am absolutely lost for words at the generosity."
Robertson was particularly moved by the comments included with donations, many resonating with the sentiment it takes a village to raise a child.
A Zumba fundraiser has been organised at the school for March 27 between 2pm and 4pm, with those in attendance encouraged to wear purple or lilac, the colours for cancer and epilepsy awareness.
A mufti-day and movie fundraiser are also being organised with dates to be finalised.