The one in your neck can be verified by touching your chin to your chest. If you get electrical tingles in your arms or down your back, it is called L'Hermitte's Sign. I would also say the one mid back is as well and if you have experienced any incontinence, bowel or bladder, it would lean towards me being right.
White Spots in the brain most times are nothing. I just had a friend who was tested for MS and I was sure she had it based on her MRI and it turns out that Migraine sufferers show white spots in their MRI's too. Not in their spine either. I'm not trying to scare you, just telling you the truth like the docs don't like too. Spinal MS used to be called PPMS once upon a time. That being said.....
I would highly suggest that you right now, not later but right now, start on a low fat organic / all natural diet and you start exercising both fine motor skills like catching and picking up stick pins off your table, strength training with some weights, and walking and or running as much as possible. Not only will it help to keep off progression but you won't progress and look back at better times with regret.