Suggest Remedy For Severe Pain In Left Arm And Shoulder

Yesterday, I was diagnosed with costochondritis by my primary care physician. He gave me both a topical anti-inflamatory cream and an oral anti-inflamatory (I am already taking methadone for my degenerative disc condition and was told to use it for the costochondritis pain as well). My question is this: The pain has now spread down my left arm and shoulder and the intensity has increased significantly. The medications I am taking are nowhere controlling any pain. Is there other medications that could give me some relief?