Should I take stress leave? When is this usually covered?

I'll begin by saying that I absolutely love my job. I have benefits, vacation time, and I work with something I'm passionate about. And I'm still under 25!

The problem is that a few months ago we hired someone to work at the same management level as me, and they(singular) make my life hell. I'd been in charge of their training and they were spoken to twice in the first month about being condescending to me. As time continued, it only got worse. They've been spoken to about 12+ times now and our manager and the manager above that are involved. HR doesn't understand the level of disrespect and how bad he is at his job, so the person isn't going to be fired unless a considerable amount of documentation is provided.

To give a better idea of the actually behaviors that are happening, I'll explain them a bit more thoroughly. We work in a small store with several employees and we are two of three that are there upwards of 25 hours a week. (We usually work about 38.) We work together most days. This person hasn't spoken more than two sentences to me during a shift for the last 2+ months, despite the fact that we should be a team. If I come within 3 feet of them, they recoil and leave the area quickly to finish the task somewhere else or do it once I won't be near them. They still speak down to me on matters related to the job despite my 2 years of experience vs. their none. They exhibit a good amount of aggressive body language if I'm present, including clenched fists and grinding teeth, sighing, flared nostrils. They also don't speak to any other staff if I'm within earshot, but if I'm in the back, on break, or even just a few feet away vacuuming, they'll start normal friendly conversation where they're laughing and talking like normal.

Objectively, I've done everything I can. I've done well, and all I can do now is wait for the documentation to add up; but I can't enjoy my job anymore if they're there. I dread going to work. I've started having panic attacks every night in anticipation of the next day. I haven't done this since high school! This is seriously detrimental to my ability to cope and continue healing. My doctor wrote me a note saying I'll be off for the next two weeks for health concerns, but am I being unreasonable? And how can I keep getting pay for this time taken? (BC Canada) I'm uncertain on how to proceed. How do I present this to my superiors? What can I do if they say no?

Advice?

I know this is a longer write up and I'm sorry if it's garbled, but stress migraines are also a problem, and I wrote this from my phone. Thanks!