Please help.my cat suddenly is thin.

My cat suddenly is thin I can feel her spinal bones and I just know something is wrong but not sure what it could be and can not afford a vet right now.please help! She is a fixed cat and is approximately 4-5 yrs old and is an inside cat

Is she eating normally and still losing weight, or did she stop eating?  Drinking water?  Using litterbox?

A vet visit really is in order.
 

She is still eating and drinking I recently got two new kittens but nothing else has changed in her life style I've had her since she was a kitten she is still using the litter box one cat/kitten is pooping blood thought it was a kitten but now think it may be her my cat,selina.

I'm not sure how sudden the weight loss is? Can you isolate her, or the kittens, to observe her behavior better. How much is she eating? Pooping? Vomiting? A healthy cat should eat about one 5.5 oz can of cat food per day. 

Weight loss can be due to any number of reasons. I would certainly try to find a vet though. There are links on this site with ideas how to find help with little or no cost.

http://www.thecatsite.com/t/155462/cant-afford-a-vet-please-read

Will do and thank you