What is the difference between the symptoms of fibromyalgia and multiple sclerosis?

I understand that MS is autoimmune and can be degenerative. And fibromyalgia is simply painful but isn't necessarily an autoimmune of degenerative disease. I am currently being tested due to severe muscle spasms in my shoulders, arms and legs, tingling and numbness in my arms, legs, hands, and feet, severe pain and discomfort from my head to my legs, major dizziness lightheadedness, and and am curious if I should be concerned about the outcome of the tests.

So far seeing a neurologist who is doing blood work and an upper and lower EMG. My primary doc has had me taking neurontin and flexeril in the mean time. But I was hoping to hear from both MS and Fibro patients, how they were diagnosed and what their experiences are...