Dural Invasion and what it means down the road....

My mother has stage IV MBC, and for 2 years, the metastases were only located in her skeletal structure. In June (ish) she started having headaches and nausea and for a while we (family) attributed them to seasonal allergies. But, after a month or so of relentless headaches and nausea and eventually vomiting, we all decided it was time for brain scan. In addition, she was itching from head to toe, which we attributed to an allergic reaction to something (lotion, soap...) and had what we thought were hives on her chest. While we were at the doctors discussing needing a brain MRI, the doc noted the hives on her chest were not hives at all, but probably cancer. A biopsy was performed and it is a recurrence of her BC. August 30, the brain MRI reported, "pachymeningeal hyperenhancement and thickening" in all adjacent to calvarial metastasis. TECHNICALLY, we don't know if the pachymeningeal/dural thickening is an inflammatory reaction to the adjacent to calvarial metastasis, or cancer invading the dural meninges. It has been suggested that because she also has a new location of BC on her chest wall, that the dural thickening is most likely cancer and not just inflammation. My Mom has opted out of chemo/radiation/hormonal treatment - essentially, she is choosing not to seek any further treatment. So, we are managing her symptoms and she has been prescribed dexamethasone, Prilosec, ondansetron. For the most part, this combination of meds is greatly alleviating her headaches and nausea. Although, we did need to increase her dex only a month after it was prescribed. My main question is what is ahead for her??? We are planning on asking her doc what might lie ahead, but honestly, he's not that talkative and I am afraid he won't really be brutally honest with us and we need to know. My Mom is scared and would feel better knowing what kind of symptoms are related to the cancer being in her dural meninges so that she can recognize them and not be surprised by them. She is extremely tired ALL of the time in the last two weeks and that is really bothering her. Is this normal? What can I tell her??? Please help us as a family understand what might be down the road.

Thank you so very very much,

Elizabeth