Needing a flexible travel insurance for a trip to Canada from Europe

Hello,

I am from France and mom and i are traveling to Canada next Monday to attend the concert of Lady Gaga that we both love. The problem is, mom had 4 intestinal obstructions since 10 years (last one 2 month ago) and travel insurance refuse to take charge of our situation because the last intestinal obstruction happened 2 months ago and a recurrence would be considered a pre-existing medical condition. I specify that we had planned the trip before the last obstruction happens. She saw her surgeon yesterday and he told her that she’s able to travel but we are scared something happens while not having any medical insurance. What do you guys think ? Do you know more flexible travel insurance ? Thank you for your advices !