I travelled to another province to look after my son who had cancer.. can I claim the travel expenses?(.flights)?

are my airfares eligible as a medical expense .

I received compassionate ei

Self-employed

Yes, in this case, it would be eligible, please refer to the links below for further details:

How do I enter travel expenses for medical treatment?

From the CRA : https://bit.ly/2IQOkOf

Footnote: Please ensure you keep all your receipts for the claim and anything referring to your travels, as the CRA may request them later.