Roseys tumor

My sweet little Jack Russell / rat terrier mix "Rosey" is 10 years old. A few years ago I took her to spay nation to be fixed. They noticed a very small lump on her stomach by her back teé.  They told me to keep a eye on it but it should be ok. So I did and it had been fine up untill like may be a month ago. It has now grown from a tip if a pen to a golf ball size maybe a little bigger.  Im wàvery concerned and everything I have been reading says it's cancer. At night often she will shake and I can tell she is not feeling well and maybe even in pain. I hope it's not but I just don't have the money at this time to bring her for the care she needs. It breaks my heart and kills me to know I can't help her. If I could raise the money to bring her to the Vet, maybe they can give her something to help with her pain or maybe do something about that lump. She is a great lovable dog. I can't image her being gone after everything she has been threw. So I'm begging if anyone can help I wil be so greatful for your help.