Here is the first thing that occurs to me, Elissa:

Most people with MS have their own pet analogies to describe their symptoms and struggles. Saying to someone "trigeminal neuralgia is like having someone drive an ice pick into your jaw" only REALLY works if the other person has had an ice pick driven into his jaw. Most people haven't!

I would suggest some "experience it yourself" object lessons. (No ice picks, of course ) For example, I've heard of someone being asked to put on one swimming flipper and trying to walk, in order to understand (somewhat) drop foot and other gait problems.

I describe the feeling in my left leg as "like wearing support hose or too-tight leggings". I have the sensation of water trickling or dripping on my skin. Moving around sometimes feels as though I'm wearing weights on my ankles and wrists. All of these symptoms could be simulated with a support stocking, a few drops of water, and some weights.

Glasses with vaseline smeared on the lenses is another example.

Of course, things such as I've mentioned would give someone an idea of a symptom, but I'm not sure what kind of props you'd use to give someone the idea of feeling like you're 90 years old!