Mom has stage IV cancer, need help finding alternatives to TennCare Medicaid

My mom has been dealing with stage IV breast cancer for some time now. Recently, things have gotten a lot worse and after a lot of convincing I was able to get her back into the hospital, but after checking her in and trying to use her normal TennCare insurance it got denied. Turns out that her insurance expired a few weeks back and she can’t renew it because I’m 19 now and in college. She has not been employed for many years and has been living off of around 24,000 dollars a month from renting out a duplex, on top of government pay until I graduated high school.

I have been looking through the HealthCare.gov website to try and find options other than TennCare, although I also re-applied for it last night since I believe (if I’m not mistaken) that breast cancer treatment and costs are covered in the state of Tennessee when living under 250% of the poverty line. I wanted to reach out and ask what the best course of action would be, if there’s any other options or if my best bet is to simply enroll into a HealthCare.gov. The prices aren’t bad at all but her savings are very limited. We’re also still not sure what the doctors would recommend because the cancer might be too far past any point of treatment, so it could just be palliative care instead. I’m also unsure how the enrollment period works, because after completing the application it said that she qualified for “special enrollment”, but was still saying that coverage would only begin after November 1st.

So far the only costs would be overnight stay, tests, scans, steroids and antibiotics, which still add up but wouldn’t be too bad. My biggest fear is if they decide to go the path of surgery and radiation and chemo that we’d be drowning in debt from it.

TLDR: I’m looking for any alternatives, private or not, to TennCare Medicaid for my mom who is currently in the hospital for stage IV breast cancer but hasn’t started any serious treatment yet.