How did you get diagnosed with Multiple Sclerosis?

About a year and a half ago I had an episode of Optic Neuritis (inflammation of optic nerve). ON is a primary indicator of MS. I had an MRI done, but no lesions associated with the disease appeared. My eye never fully healed. Since my episode of ON, I have accumulated many other bizarre symptoms associated with MS. My joints are very painful, my leg muscles twitch a lot, I have muscle pain, slight ataxia, my muscles don't have much stamina or endurance, my extremities often fall asleep easy. Basically my body is usually in some sort of pain or discomfort. I know it's not in my head. I have noticed a steady progression of symptoms since my ON. I'm a 27 year old male and my grandfather had MS. Any insight or thoughts regarding the disease and how some of you might have been diagnosed. Another MRI? Neurologist? Help please.