My mom has dementia and is in a nursing home. When I visited, I discovered a big unexplained cut on her leg. What should I do?

The nursing home investigated who and what injured my mom. They interviewed the aides who dressed/toileted/bathed her - none of whom admitted to seeing any injury - even tho the wound was several days old when I saw it. Supposedly, the aides were re-educated and a note put in their files (nobody was fired). I asked the nh to provide an aide for my mom until I could arrange to have her moved to another facility (since I am currently unemployed). They refused, stating that is "against their policy." They promised to keep a close eye on her but at this point I don't trust them. What should I do? I would like to see if I can raise some money from other relatives and hire an aide but I would also like some tips on how to hire someone who is dependable and not another threat to my mother. Any suggestions on the hiring process?