Nervous about MS, but need a diagnosis!

When I was about 5 years old or so after being pretty sick with mycoplasma for three weeks or so, my left leg (mostly just above my knee down to my foot) started giving me problems-- it would just 'give out' when I was walking, I remember it having this ache on the inside that made it difficult, painful, and frustrating to even walk to a friend's house down the street. I went through a ton of tests to rule out bone cancer, ortho problems, and did an MRI of my lower back, all of which were clear.  Leg problem would surface every now and then around that time, but doctors kept saying "growing pains" or sports injury, so my parents decided not to worry.

When we moved a year or so later, the symptoms seemed to resolve themselves! I was a cheerleader, figure skater, an overall pretty active kid (about age 8-13) with no real symptoms of whatever was going on before. Here and there, my left leg wouldn't really work right or kind of hurt a little, but I always attributed it to 'playing too hard' ;)

Since then (I am almost 21 now) my issues with my left leg have gotten progressively more complex (moving all the way up to the back of my head) and a bit more painful.. but always just sporadically, never constant. In the last 1-2 years, however, the symptoms seem to have exploded. They include:

-numbness/heaviness in my left leg and left arm, as though they are asleep
-shooting, electric-like pain from my hip through my toes
-a 'gripping', dull pain in my arm and hand
-odd finger and toe spasms (infrequent, but quite annoying)
-tingling, like cold water up the back of my neck and back of my head
-what feels like a painful air bubble in my chest-- I have to breathe very shallow breaths for about a minute or 2 to make it go away
-tightness in my abdomen.. the best way to describe is like I'm wearing Spanx (girdle) and just ate a huuuge meal or drank a gallon of water, or like my stomach is full of cotton
-constant urge to urinate, whether or not I even can-- similar to the feeling of a UTI but no burning nor infection
-frequent respiratory issues (in fact, every time I've been sick in the last several years, it was something to do with my chest!)
-Always fairly constipated
-a couple instances of dramatically unequal pupil dialation (once about a year ago, once last week) lasting about 8-12 hours. The first time, the hospital did a CAT scan, but it was negative.
-pain in the left side of my jaw and the cartilage of my left ear-- like the whole part of my ear you can grab -- usually lasting only a few seconds, but when it happens it's several times per day for 2-3 days

There are other random symptoms, but these are the ones that happen the most frequently. Usually when they occur, everything hits me at the same time for a duration of about a week (more or less) and leaves me feeling completely wiped out for several days, as though no matter how much I sleep I still wake up as though I've been running all night.
I saw a neurologist a few months ago who ran all the typical neurological evaluation tests, which I passed with flying colors! I also had a MRI of my brain which looked very normal, Nerve conduction, EMG were both normal too.. So why is everything in me falling apart?! After doing a lot of research about my symptoms, my mom found that MS symptoms were very similar if not exactly the same, so we searched for an MS specialist to give a second opinion. By some miracle, I got an appointment with a neurologist at Duke who I unfortunately had a terrible experience with. He spent five minutes with me, looked at my brain MRI, did the standard neuro eval tests that my main dr did, and pronounced that I "probably have an eating disorder"(likely responding to my GI symptoms), told me I don't have MS, told me to go see a general doctor and psychologist, literally said, "but thanks for coming in", shook my hand, and left.  Once I regained my composure from having yet another Dr. just shrug me and my symptoms off, I drove the 2.5hrs home.

I went back to my main neuro, who after hearing about my discouraging appointment with the specialist, decided to prescribe Topamax to see if it at least helps with any of the symptoms-- I've been taking it as directed with a very open mind, but it doesn't make any change, besides making me feel slightly drunk. I am at a loss as to what I am supposed to do now-- everything I have read recently says things about a spine MRI, evoked potentials, or lumbar puncture that may help me to find a diagnosis, so I plan to schedule a followup appointment to request, or at least ask about, these procedures.

I know this has been a very long post, but I feel like if it's not MS (which based on my lesion-less MRI, it isn't) then how can I find out what it is?! Any help or advice anyone can provide would be wonderful.