Dog surgery

On april 2019, my dog started to crying in pain, cant shit or pee well.

Went to a vet and the vet advised us to let them take samples from my dog and do a xray. After the xray, my dog was found with a big lump! They then advised to do a ultrasound to determine whether its fat lump or cancer before doing any surgery. After the ultrasound, they still cant determine so they suggest to cut bits of the sample to see whether its cancer anot, but then i do not have any fund as im a student and i come from a poor environment. So my parents cant afford to pay for further treatment, so i only got some medicines to reduce her pain and it cost almost 400 over dollars. Right until a week ago, my dog start to cry in pain again and i realized her lump is getting harder. I really dont want to give up on my dog but i dont have the income at all to go get a surgery / treatment for her. I would like to sound out to my fellow dog owners to spare a dollar and help me so i could go get a surgery / treatment for her. Every dollar helps !