I will take a stab at this. I can see both sides of this, and it is a pretty tough situation. On the one hand, you don't want to go chasing diagnoses; on the other you don't want to ignore a possible serious illness.
My advice would be, if you're experiencing neurological symptoms - see a neurologist. If you need a PCP's referral, get one. Then have a full workup, including MRI's, exam, blood tests, etc. If you're not happy with the first neuro, get a second opinion. But at some point (for me it would be after the 2nd opinion), you need to use your own judgment, and stop. If all the tests say you don't have MS, then I would go with that. True, sometimes the standard strength MRIs don't pick up all damage. And the lumbar puncture isn't always conclusive. But there's only so much testing you can do. And it doesn't do any good trying to self-diagnose based on knowledge gleaned from the internet. True, the symptoms can be difficult to deal with from day to day, especially when the cause is unknown. And some doctors are better than others, and some are more dismissive than others. But it isn't good to think you have a terrible disease like MS, when there is no evidence for it.
One example that I can think is similar (and I hate to really use this) is Lyme disease. You're probably aware there are many forums and internet sites devoted to lyme disease (and if you're not, don't go looking for them, and definitely don't mention them on the anxiety forum). The arguments usually are along the lines that almost all symptoms a person can have are symptoms of lyme disease, and it mimics many other diseases, like MS and ALS. And the blood test are unreliable, so even if you test negative, you could still have it. So, many people believe they have it. And I got caught up in this. When i was being worked-up for MS, my GP told me I have Lyme disease. I started the long-term antibiotics he recommended (though not convinced), and soon developed another infection related to the antibiotics. I promptly stopped and never went back. In the months that followed, I often wondered if it could really be Lyme, but now I'm more convinced I did the right thing.
So, my advice would be to get the testing done. If it doesn't look like MS after a full work-up, move on with life. Easier said than done, I know. But let me say this. I got diagnosed with MS about a year ago. And physically, I haven't changed that much yet. But after getting the MS label, something changed for me. If I hadn't been given the diagnosis, I think I would have continued with life the way I was, just dealing with symptoms when I had to. I'm not saying I would have been better off not knowing, but now I see things in a different light, and not necessarily a good one.