My 14 Years Old Spayed Lady Cat Acts Normally But

My 14 years old spayed lady cat acts normally but we discovered today big spots of blood stains on her sleeping mat. Normally means she eats and sleeps in the same routine as usual. She still oves to be petted and seems quietly happy. She is a feral cat difficult to bring to the vet but we will do it between the two holidays.
We are worried because there is no apparent wound. We saw some stains on her rear right paw but there is no wound there. Can it come from her rear end that lies on her paws when she sleeps? I just discovered a lump in her abdomen (right side). It might only be a kyst but again there is no wound there either.
Thank you very much for her and for us.

Daniel