bilateral burning really does sound like it would be coming from the lumbar spine - perhaps get some investigations. Have you tried a mckenzie approach to the spine? it's worth a go if it's been a month and she isn't getting better. It sounds like she's already had alot of treatements - all of those in a month? how long has she had each treatment for... perhaps a longer course of one of those treatments would show a positive result.
sounds very interesting, sorry to not be huge help, let me know if you work out what it is.