What Causes Pain In Upper Muscle Of Arm While On Rizatriptan Benzoate?

Hi, I am 57 ,female and have I ve had tight pain in upper muscle of left arm for a few days. It feels similar to the restrictive pressure of a blood pressure cuff and is becoming constant, not eased by anti-inflammatories. The only med I take is rizatriptan benzoate for migraine. Thank you for your time. Robyn