clem, I was recently diagnosed with MS. I had an MRI of my head and neck, and a neuro examination. They found lesions on my scan, but very 'faint' ones (I think that's how they described it). I think the diagnosis came mainly from the description of my symptoms, and the history of my symptoms, and the scan simply confirmed it. Lesions can apparently be there without it being MS, Also, people with severe symptoms might only have a few lesions, and vice versa, so the lesions aren't (I think) the most diagnostic aspect.
My symptoms were random (mild) dizziness, then a numb torso which went away after a month, then a few months later, tingling in hand and legs, plus a sensation of wearing wet jeans when I walked - a kind of clammy, dragging, cold sensation. I also have a little bit of a flicker in one eye which means if I shift my focus it takes a moment to adjust. Plus lightheadedness and dizziness. The symptoms were quite severe for about 6 months, then they died down quite a lot, atlhough are still there now.
Anyway, hope that's helpful. Try not to panic too much. The fact that things are being investigated is really good, because whatever you do have, you can hopefully get treated early.