How Can Cellulitis On The Legs Be Treated?

I work in a SNF as a speech pathologist treating an obese 94 year old female who has been diagnosed with cellulitis of both legs. She was put on flagyl and one other antibiotic but those have been completed. Her edema, redness have been increasing over the last week. It initially took the MD 4-5 days to respond to the RNs request for advice on treatment. He finally prescribed a diueretic. Her symptoms are worsening. She can barely walk. I report this to D.O.N. Who had originally contacted MD. The MD is just requesting weights. No additional treatment has been prescribed. She saw her primary care MD yesterday who told her to use Vaseline. I am very concerned. Please advise. Thank you Susan