cat is walking flat footed

this is a long one. my friends cat was a stray they took in a few years ago. he had trouble pooping and would get incredibly constipated and not eat. he had a broken/ dislocated tail as well. after taking him to the vet for the constipation issues, the vet found that his hips were completely misplaced (explaining the tail and constipation issues). we assumed he was hit by a car sometime in his youth. the vets recommended euthaniziation. instead, taking a last risk to give him quality of life, my friend had his tail removed, and started him on a laxative diet. he has been living pain free like this for the past 2-3 years with the occasional need to increase his dose in laxatives. out of nowhere, his cat suddenly began walking flat footed (see photo included) on one foot. they have no idea what's wrong. to top it all off, they are financially struggling, no vets around us take payment plans, and only recommend creditcare, which they don't qualify for. just looking for what could be wrong with him, and options for vet care. and possible answers or recommendations is extremely appreciated. they're doing everything they can while we try to locate a vet or figure out some type of situation to help him.

this is a long one. my friends cat was a stray they took in a few years ago. he had trouble pooping and would get incredibly constipated and not eat. he had a broken/ dislocated tail as well. after taking him to the vet for the constipation issues, the vet found that his hips were completely misplaced (explaining the tail and constipation issues). we assumed he was hit by a car sometime in his youth. the vets recommended euthaniziation. instead, taking a last risk to give him quality of life, my friend had his tail removed, and started him on a laxative diet. he has been living pain free like this for the past 2-3 years with the occasional need to increase his dose in laxatives. out of nowhere, his cat suddenly began walking flat footed (see photo included) on one foot. they have no idea what's wrong. to top it all off, they are financially struggling, no vets around us take payment plans, and only recommend creditcare, which they don't qualify for. just looking for what could be wrong with him, and options for vet care. and possible answers or recommendations is extremely appreciated. they're doing everything they can while we try to locate a vet or figure out some type of situation to help him.