What Causes Severe Pain And Weakness In The Legs?

I m 53 female. At 13 diagnosed with juv dermatomyositis. Weaned off prednisone in late teens. Is it coming back or maybe some other auto immune disease? I have severe pain in muscles of legs and weakness. Currently taking 40mg prednisone which has made pain subside and 2nd regiment of Zithromax for sinus and ear inf. Diagnosed A month ago with hypothyroidism and also had had a very enlarged lymph node with Ct scan. This month Had elevated CRP, lymphocyte, and eosinophil. Also had 3 other tests specific to dermatomyositis which were neg. all cervical lymph nodes are enlarged to where it feels like it s hindering my breathing. Thought prednisone would reduce the swelling. I have an appt in late May with rheumatologist, hope I can last that long. Is this the right type of dr I should be seeing?