What Causes Weakness And Shaking While Having Fibromyalgia?

my partner has fibromyalga his left side has always been week and occasionaly shaky but now his whole body very week and shaky. very hard for him to even stand/move. he is in full body pain most of time but past few days it has all been much worse. i have never been happy with his diagnosise, but all the doctors could say at time.