Based off of letters from Jane Austen and others, it seems as though Austen dealt with health issues for a lot of her life, and the most serious one (which ended in her death),  first took hold at the beginning of 1816. This illness is unknown, but it's been theorized that she may have had Addison's disease or cancer. She describes having fever, weakness, and languor and being bedridden with this illness. Her and Cassandra eventually left their house in Chawton and moved to Winchester, seeking improved medical treatment. Unfortunately, the Winchester surgeon that treated her declared that in her condition, it was, "impossible for any person to last long". Austen spent her final days in Winchester surrounded by her family, and died on July 18, 1817. She was buried in the Winchester Cathedral, where you can still visit Austen's grave today. 

Looser, Devoney. “The Final Years of Jane Austen and Her Death.” Wondrium Daily, Wondrium, 20 Sept. 2022, https://www.wondriumdaily.com/the-final-years-of-jane-austen-and-her-death/.