I don't know about this particular essence for this particular illness, but used to work for a co. that makes flower essences, and have made and used a lot of my own.
Flower essences are basically homeopathic, which means their action is really not understood. Unless you have a problem with the alcohol used to preserve the essence dilution, they can't possibly hurt you. (If you do have problems with alcohol, get a blend preserved with vinegar or glycerine. They don't taste as good, but it's just a few drops.) They may help; there are many instances of physical problems being helped with flower essences. But as we know what works for one in this illness may not work for all.
I think they are worth a try for you. A good practitioner will pay attention to you and what's going on with you; you might even wind up getting a different remedy (or blend of remedies) for your condition.
I'm so sorry you're feeling desperate, how well I know that feeling. Herbqueen, you may want to check out a methylation protocol as well. I have made only moderate progress on mine, but it seems as if removing some of the methylation block makes it easier for other protocols and remedies to work. Others have said the same.