I am a store manager for a big retail company in Toronto. Stress is killing me lately. I have chest pains and weird dreams, I'm nervous at all time, etc. How does stress leave work? Do I need a doctor involved here? Does the company pay me, or does someone else?
This depends very strongly on your employer. If you are at the point where you cannot work then to be honest I don't think there is any downside to going to HR. A big retail company is sure to have one. If they are useless and unhelpful you have lost nothing by talking to them because you were going to leave anyway. They might well surprise you though.
If you are covered by short term disability you may be able to stop coming to work and collect that disability payment instead. Typically there is no waiting period for short term disability. However you must be diagnosed by a doctor; you can't just announce your own diagnosis. Further, the insurance company will demand that you be treated - therapist visits, medication, etc. You can refuse to accept certain treatments, but they may suggest the coverage will stop if you do - this may or may not be a true threat.
I had a staff member whose approx. 4-year-old was diagnosed with cancer shortly after his marriage fell apart. He was unable to work and was of no use to me (he kept coming in, but was getting nothing done) so I told him to go on the disability so that I could stop paying him. They would only confirm his coverage a week or so at a time - this added to his stress significantly. He strongly resisted seeing a therapist but they insisted and in fact I believed it ended up helping.
If your company doesn't have short term disability, they may "self insure" - that is, pay you even though you're not coming in. The HR person would know this. If they have nothing at all that will help cover your salary, then you can talk to someone at EI about making a claim. This will likely involve giving up your job completely (though your employer may tell you they are willing to hire you back later) and applying for EI. Your eligibility will depend on things like how many insurable weeks you have worked.
There are people who will help you with this, but you have to reach out to them. Some, like your managers or HR, can try to reduce your stress at work, though that's a tall order in retail during November and December. Some, like HR, can tell you how to apply for short term disability, and let you know what to discuss with your doctor. Your doctor can help you not only with qualifying for various income replacements, but with actually handling the stress and the physical symptoms it's causing you. The folks at EI and your insurance company may help keep you fed and housed while you deal with the stress. There is a whole army of people for whom this is their job. Swing them into motion now, while you still have the strength. Don't start with a lawyer; that's for when the nice, pleasant things don't work.