You are a huge help!!At a high level, you do appear to have a decent case considering you can speak English and presumably have been working in Canada with your (again assumption) minor child. Thus, I am surprised your case has been rejected.
I was a teenager when I started doing research related to immigration regulations for my parents so I do believe you seem to check off most boxes. But it also depends on how long you have been in Canada - the longer you have resided in Canada, the stronger your case becomes.
I think I need to quit engineering and go to a law school and become an immigration lawyer because I find things like that pretty interesting!
My daughter (a minor) and I have been living in Canada for a little over 10 years now. I was working in Canada the last year or two because my family couldn't financially support us anymore so I had to get some income.
For her skin condition, we sent proof (pictures) and letters from my daughter's doctor. Everything from what she eats and even foods she touches effects her in our home country. But even if we're not too cautions, she's completly fine in Canada.
She gets prescriptions when we are in our home country but the medications are super strong for her so her body sometimes takes a toll (Migraines, headaches, stomachaches, muscle pain, vomit, etc)