WARNING FOR USER @shadowycollageatfunny.
This user has a history of scamming people and creating fake fundraising posts to solicit donations, having stolen people’s private photos to misrepresent their situation - in this instance, lying about their “sister’s” health problems. As you can see from the “evidence” they’ve included in their post, these medical documents have very obviously been doctored - the fonts used for the names, diagnosis and dates are completely different from the rest of the documents, and you can clearly see where the original information has been blocked out and replaced. This user has changed their story multiple times, and uses multiple sockpuppet accounts to try and ‘corroborate’ their posts (for instance, @keepintoyourself is pretty clearly a sockpuppet), as well as harassing people who have noticed their behaviour. Another red flag is that the PayPal account used by this account has been changed several times, having been flagged for scamming and fraudulent behaviour. Do not donate to this post, just block this account and report their post to Tumblr and PayPal. They will likely just delete this account and start again with another fake story.
@donationscamwarning and @donationscamalert have more resources on how to recognise active scammers.