The vet took x-rays and there has been considerable bone loss since last week. He said it's cancer. He cleaned up her mouth the best he could. We'll start her on pain management and when it's obvious her quality of life has diminished so that she's miserable and sick, we'll say goodbye.
Having dealt with squamous cell before, it won't be long. If it's grown this fast in three/four weeks, there isn't much hope.