Side effects or something else? - 1293708

I was dx with stage 4 nsclc, EGFR and t790m + 2 yrs ago. Aside from this, I am a healthy 44 yo (except migraines since childhood). After radiation to a few spots on pelvis and spine as well as VATS lobectomy, then Tarceva and now Tagrisso 80mg, my scans currently show a small 7mm nodule and nothing more. However, I am feeling quite debilitated, and have been with most of mt treatment.
Tagrisso has been easier in many ways than Tarceva, but I am plagued by profound fatigue, lightheadedness, ongoing dizziness, blurred vision and pronounced flushing at times (often coinciding with feeling faint and nauseous and most often when I am busy or been walking).
The Tagrisso had reduced my appetite significantly, so I began mirtazapine which has done wonders. I'm drinking and eating much like I did before treatment and overall, feel much less weak and tired. However, the other symptoms remain and make it very hard to be productive. As I type this it feels as if the room is spinning and I have to close my eyes from time to time.
I know some of these symptoms are common with Tagrisso. They seem to be getting worse, not better the longer I am on the drug and are really the only things limiting me at this time. Those limitations however are significant and greatly impair my daily functioning.
I'm curious if it is the Tagrisso, is there a case for reducing the dose? Are there more likely culprits like menopause (which happened almost immediately with beginning treatment) or blood pressure problems? Any guidance would be greatly appreciated! Thanks.