Low Dose Olanzapine/Zyprexa? (Or other anti-psychs)

So I've been working with a psych to try to address my PMDD and have really gotten a point where the only struggle I have is 1-3 days of extreme mental distress and mood swings at the beginning of luteal.

My doctor recommended a low dose olanzapine/Zyprexa (only 2.5mg), taken only during the week before I get my period. Has anyone done anything similar? According to my research, this seems to be a very unorthodox way to use olanzapine, as well as an unorthodox method for treating PMDD. Still, birth control and SSRIs do not work for me so I'm willing to try it. Plus I actually trust this psych and her creative solutions so far, hallelujah lol. But I'm a little scared of starting it because of the intense reactions people have at 20mg.

If you've never tried Zyprexa but have tried low intermittent doses of other anti-psychotics, what was your experience?