@jlw — I was reading through several of your posts and noticed that you have been to Mayo Rochester and had genetic testing that determined you didn't have DM2. @becscuddy had a link to another discussion for Distal Myopathy which it looks like you saw and possibly read through the discussion — Did you see the link to the Myotonic Dystrophy type 2 discussion? https://connect.mayoclinic.org/discussion/myotonic-dystrophy-type-2/
My experience with steroids is with prednisone for PMR and it was pretty same day effective to eliminate the pain. Did the initial dosage of 60 mg daily reduce your pain symptom? Just wondering if you are able to discuss it with your Mayo neurologist.