I have no experience with any type of dystonia, but I do have lots of experience with illnesses and injuries that traditional medicine could not cure... and usually I found a cure or treatment. The proof is that I'm still running after being told that my injury meant that I could never run again, that the illness I had was untreatable and that I would have to live with it, that multiple tests showed that I was normal and I didn't have a problem! Well, I'm still running because I found a solution in each of those cases.
You need to look into alternative (complementary) therapies. Don't expect to find any studies... just see what others have tried that worked for them.
You could start by...
Doing a Google search for dystonia support groups and join them. See what has worked for some people.
Join the Facebook Dystonia Support group. See what has worked for some people.
Do searches for dystonia alternative medicine, dystonia treatments, dystonia complementary therapies.
My experience with alternative therapies is 15/85... That is, 85% of the time, the alternative approach won't work, but if you're persistent, you might find the one of the 15% that does work.
When I find an anecdotal testimonial, I ask three questions: What is the financial cost to try it? What is the health risk of trying it? Have several people found success with this approach?
For example, on a whim, I did an Amazon search for dystonia. Typing in dystonia gave me a lot of second words... dystonia brace, treatment, book, and so on. Looking at the books and devices gave me a general sense of what others might be trying... yoga, neck braces... and neck braces gave me the idea that chiropractic might help since the signals move from your brain to your legs through the spine, right? At least I would have an idea of the general areas to look into.
Bottom line: What your doctors are doing isn't working so you need to be proactive to find something that does. That means you might have to come out of pocket to pay for some alternative therapies that don't work until you find one that does work.
Example: I had severe lower back pain last fall. It was so bad that I couldn't run. My sports doc couldn't cure it. I asked around and finally saw a couple of chiropractors and a physical therapist. After about 4 weeks, I found an approach that worked!
The irony is that the approach that worked cost only $20, but I had to spend over $1,200 to find it. To me, that $1,200 was money well spent even though most of it was spent on the 85% of things that didn't work.
Anyway, I hope this gives you some optimism. If you're persistent, you can probably find a cure or a treatment that will allow you to continue running at a high level.