Someone correct me if I'm wrong - I believe I was told muscle spasms can occur from a lack of potassium and diuretics could deplete potassium in the body which would explain why one happened after the other...? Does that sound right? But, I always thought of feet and legs....not backs spasming from it.
Also, I have a lot of muscle issues that do occur when I get a flare...something about the swelling hitting a nerve or muscle it would seem. Or maybe the muscles/nerves are swelling too, I don't know.
Sorry, I know that isn't much help. Someone more helpful will come along soon.