My kitten, who was given to me by someone from church, right at 6weeks, well 1st off let me tell you about her: she's a little over 6months maybe 7 or even 8 I do not fully remember, just not a year she's like a little over 7months (by a few days over) and she has a lump on her LEFT side, right in the middle of her arms and lefs, on the side. It's the size of a tennis ball , prollu a little smaller, by the feeling of the size, by my palm its little smaller then tennis ball. She runs around the house, and has falling FACE FORWAD off my moms quilt rack, but we cnat afford a vet, and I have lost many cats (due to scared of new family, bro squeezed last one causing his blatter to bust/ and well yea for any info like such if you need let me know) and I WILL NOT LOOSE HER! What should I do? What can it be? And SHE IS ONLY CAT, NOT VACCINATED BUT NEVER BEEN OUTSIDE OR ANYTHING!! Only time she was EVER outside of our house doors was when we brought her home! :)

That is an awfully large lump for a cat. Can she walk or does she fall over when she tries to walk?

That is an awfully large lump for a cat. Can she walk or does she fall over when she tries to walk?
SHE can walk, she is a normal size , it's a little smaller then a tennis ball, from the felling of it on my palm, its down a little more past middle towards her leg

How long has it been on her and does it keep getting bigger? It may be a tumor and only a vet can help you with that.
Are you sure that your brother has not harmed her?
How old are you?
Are you old enough to get a part time job to help out with vet care for this cat?