Virginia Giuffre, who accused the now-deceased Jeffrey Epstein of sex trafficking, has shared a troubling IG post from a hospital ... claiming docs have told her she has 4 days to live -- now down to 3 -- after an apparent car crash.

In a Sunday IG post, Giuffre shared a photo of her bruised face from her hospital bed ... asserting in the caption that she went into renal failure after a school bus crashed into her at a whopping "110km" (68 miles per hour) while she was slowing down for a turn.

Giuffre claimed her injuries were so severe that doctors gave her just days to live and transferred her to a specialist urology hospital ... but despite supposedly being at death’s door, she still managed to muster up the strength to update her IG followers.

She seemed to accept her alleged fate, writing she was "ready to go" but wanted to see her kids one last time, but seemed to cast doubt on that happening -- and ended the post by thanking her fans for being a great part of her life.

Right now, the details of Virginia’s hospital visit are unclear ... and there don't appear to be any media reports from Perth -- the city where she lives with her 3 kids -- or anywhere in Australia confirming her claim of a car accident involving a speeding school bus.

Along with Epstein, Virginia also accused Prince Andrew and Ghislaine Maxwell of sexual abuse -- Maxwell is currently serving a 20-year prison sentence for child sex trafficking in connection with Epstein. As for Andrew, she sued him in 2021, but they settled out of court in February 2022.

We've reached out to attorneys for Giuffre ... so far, no word back.