Do We Need MRI In Case Of Intense Pain In Arms?

our son aged 23 has bouts, maybe 3 to 5 times each day of intense pain in his arms and hands. this has occurred over the past week. these bouts can be set off by lightly touching his hands arms or shoulders or without any contact wit his body at all. his x rays and blood test have been returned without indicating any significant signs. we are waiting for a neurologist to see him but getting even a private appointment may take several weeks. he takes zydol, co codamol and atriptalyne(?) for the pain. we are waiting for an MRI scan to be done, Have you any experience of such a condition, possible diagnosis and suggestions for his treatment?