Help Us Cover Ollie's Medical Bills

Ollie is my world but...Rent is due at the same time, and whichever I pay is going to leave a consequence. I need help, please. They had me put down a deposit of $500, $300 to get him back. At this rate I couldn't afford to get him decent food and litter.  I don't know if I could raise the whole amount but hoping to! He still needs to go back for a urinalysis which is additional, but I'm praying to recover a portion of the cost. Thank you to everyone who poured their advice! I'm a first time fur-parent who definitely didn't know what I should do >.<