Did you have the blistering rash when you were first diagnosed? It could be that they are just coming up now. I would get a blood test to be absolutely sure that this is what you have. I have never known it to last for so long, but I am not an expert or Dr. In the mean time here are some home remedies that you can try to get some relief.
You can apply wet dressing to soothe the burning sensation
Avoid being in humid areas. Always keep yourself cool.
Keep the blisters open and dry. Do not burst the blisters by scratching.
To provide relief, make a solution by mixing 1/2 cup of apple cider vinegar in 2 cups of water. Use a cotton cloth to moisten the affected areas by using the upward movement.
Baking soda and water solution can also be applied as a cold compress.
Avoid food which contain amino acid such as chocolate, cereal grains, nuts and seeds.