What Causes MS? Or where do vaccines figure in all of this?

Just reading a thread on the very helpful site, Patients Like Me, where I routinely go when I want to ask a question that my doc would look at me sideways for asking.
They've been there when I wondered about which treatment to take, when my legs started spasming and no one seemed to think it was a common thing with MS, when I lost sensation.  They've been helpful, and they have additional sites for other diseases where fellow sufferers get together and share information. It's great to look up medications and see if others have been prescribed the same things, etc. Awesome resource.
However, it is filled with people who are desperate about MS and also somewhat uninformed. The latest post is filled with suppositions that vaccines caused their MS.  Now, we don't know what causes MS, so I can't be SURE they are wrong, but research says it is probably a combination of things - from low vitamin D, to infection with Epstein-Barr disease (mono) after age 15, to stress, to a variety of other things from genetic tendencies to environmental pollution. Maybe vaccines do play a part, but I hate to read these posts.
Why?  Because I'm a nurse, and I know what those vaccines prevent - diphtheria, where a thick membrane forms across your throat, disabling your ability to breathe; rubella, where infection during pregnancy results in a deaf, severely congenitally damaged child; polio, which leads to paralysis with first infection and often recurrent paralysis later in life; pertussis, which I've seen kill babies with exhaustion; tetanus, which paralyzes the lungs and can kill. They aren't minor diseases.  We've become casual about them because they are now rare, thanks to immunization.
My son is travelling through Asia and caught amebic dysentery.  He is taking pills to forestall worse infections: malaria, sepsis from any wounds, etc. But what is primarily protecting him are his immunizations, for hepatitis, yellow fever, etc etc etc. He is wandering safely through a literal morass of germs and creatures all hoping to feast on his remains. As am I, here in safer North America.

We have so many little bugs who are becoming resistant to antibiotics that immunizations are becoming even more important year by year.  I take my flu shots.  I need to get my tetanus updated (tetanus is in the soil and can getcha anytime - you need a booster every 10 years).  I can't prevent my MS or my diabetes or whatever, but I can do what I can to keep myself from being felled from diseases for which we have the prevention available. Why wouldn't I?
I wish I could finger the blame for why I have MS.  There isn't any in my family; I don't know why I have been so lucky.  Inside myself I blame a bad case of mono in College and my second to last boss, who stressed me to breaking point. But I don't know.  It doesn't really matter in the end for me, though I'd like to see the cause identified so it could be prevented for others.
But fear of vaccines has its own dangers...