Help my dog

3years ago clover was brought to us since she her pet owner cant take care of her due to rental issue and left to us but promised that he'd go back and get clover but never he did. She was a small and naughty puppy back then. So cute. Then few months ago she got a mange, until now. Because im the only one working in the family and since my salary is just enough for my family i couldn't afford to bring her to vet and to provide her medication. I dont even know if her mange is just a simple mange or a something much worse than that coz no matter how we feed her she is still thin. Please help me bring her to vet and have her check by a vet and make her healthy again. Thank u for those who will help.