Welcome to the board! I hope u'll feel comfortable asking anything u need and know we'll all do what we can to answer u'r questions/concerns to our best ability and extent of our experiences.
There are a lot of tests run to rule out many things when considering MS as a possible dx. As u've already said, there isn't any one test to rule it in. I've prob had all the blood work most often ordered, but can't tell u the types/names of tests done. I'm sure others will be along very soon to help with that, but know there are many. In testing for Lupus i'm sure u were also cross tested for many of the same things. In addition to the blood work usually done, there are evoked potentials which measure the speed and effenciency that nerve impules reach the brain, eye and ear. Also, as u mentioned, MRI's. Usually done of the brain and spine and sometimes of the lower and mid spine if the doc feels needed. Usually as a last resort a lumbar puncture (spinal tap) will be performed. This is not the test of choice to begin with, but rather is used most often to confirm other test results that give reason to suspect/believe ms is the culprit. Of course there are the in-office exam tests done; like heel to toe walking, strength testing by pushing against the docs hand as hard as u can, standing with u'r eyes closed to see how long u can stay up and straight, reflex tests and many more that i can't remember. I'm sure i'm forgetting many...one of the wonders of this nice condition. By the way, i'm in limbo as well. I've been here...unsure of what's going on with my body...since Feb of this year. Limbo can last a long time or it may not last any time at all. I hope and pray u'r not in limbo for too long and will get some answers soon. U'r question about lesions showing up so soon after symptoms starting...well yes and no. I had my mri's pretty soon after my symptoms first began and didn't have any lesions. That could mean i'll never have any lesion and don't have ms or it could mean that it's just so early in the disease that they aren't showing up yet. U should follow u'r docs lead for now and see where he's going and let him do his job, but in the end if u'r still left with no answers and u know of things that can be done...spinal mri, lumbar puncture...then by all means ask for that if it'd put u'r mind at ease. I've learned tho that even when u don't see any answers u can still trust that u'r doc's doing all he can do at the time, but if at any time u feel unsure or that u'r not being given due care and effort to resolve this, u should act. I hope i haven't missed too much, but i know i have missed some. Others will be along to help with info as well. Again, welcome to the board and i hope u get some answers very soon.