If the steroids are making you worse, you don't have to take them...talk to your doctor immediately. Don't stop taking them on your own but let your doctor know. There must be other treatment options for myositis besides steroids.

I don't understand why you are getting multiple new treatments at once...the fluids and vitamin D should be given time to see if they are helpful before starting another treatment, at least that is my non-doctor opinion. How will you know if these two are helping if you start steroids, too? I'm confused.

I want you to receive the best treatment. You were just feeling better recently, right?

Sorry if I'm missing something, but it seems to me that there should be a delay before starting steroids. Please talk to your doctor.