Could she have been kicked? :(
I’m with you, I’d vote for the miserable excuses for renters having kicked the cat and caught her on the flank. The vet will be able to tell whether her injury is consistent with abuse.
Her biting is no doubt due to pain, although I once rescued a cat that put both my husband and I into the ER overnight (at different times) on IV’s due to her sinking her teeth next to our thumbs. She turned out to be a great cat, but I learned not to put my hands on her unless sure of her mood.
The cat will have you up to speed in no time, not to worry.