year old female present i...

A 24 year old female present in ED with tender nodules present over elbow both sides and other places i.e on great toe and buttocks. History of painful joints more ankle than shoulder , knee and elbow. Pain intensity remains same all the day. No fever Cbc within normal range Crp normal Esr mildly raised Ra factor negative Anti ccp negative..  What is the next diagnostic test and line of treatment