Hello:
Hope you are doing well. My condition is similar. I have myotonic dystrophy type 2(genetically confirmed)Both myotonic congenita and myotonic dystrophy fall into the muscular dystrophy umbrella. You already know that - it is geared more toward the folks that aren’t familiar with the myotonic diseases.

Have you checked into the MDA (muscular dystrophy association) clinic at Mayo? The program is excellent and helped me out immensely. They can work with pain management, bio-feedback - just a overview of all that they can help with. You will work with OT and PT to help with strategies for daily living, exercise routines, stretching routines, diet.

The docs you will meet with are specialists in different types of muscular dystrophy.

Which state are you in? If you are in Florida, I can give you the name of the neurologist that i work with at Mayo.

Pain management can be tricky as there are not a lot of normal pain meds that are effective with the type of pain we feel. Also relief from the muscle cramps are very difficult to manage because of their transient nature.

I tried metaxiline which couldn’t tame the pain. We titrated to the max dose and it gave me hallucinations.

Muscle cramps in my case are complicated because of Parkinsonism.
Do you find that you can trigger a cramp from running into something (I’m becoming a bit clumsy). - even lightly you get a cramp? When I am playing with my grandson he will give me an enthusiastic thump on my shoulder and cramp city. These are not very hard impacts.

The only thing that helps for me is a good ratio product of CBD with a very small amount of THC. In my case - i utilize a 12.5 part CBD to 1 part THC product that helps with the pain and muscle cramps along with a plethora of other things like mood, flexibility and sleep. This also helps with the Parkinsonism.
My neurologist says - if it works then - utilize it. We both know there is no cure and whatever treatment we get is to make life more palatable.

Sorry to not be able to give more of a definite answer as to what works - the choices are limited.

If you find something that works for you - please share it.

Stay safe and well.