What Causes Muscle Spasms While Having Ruptured Discs In Cervical And Thoracic?

I have severe muscle spasms and the neurologist said it is caused by cervical dystonia even though I have no pain in my neck or shoulders. I also have ruptured discs in the cervical and thoracic area. He has suggested botox shots but is hesitant since I am sensitive to meds. My question is, how do I know these muscle spasms or from the cervical dystonia or the ruptured discs and what treatment is recommended?