Multiple sclerosis.. . Can it be mis-diagnosed because the symptoms are so vague?

Yes. Is better to see a neurologist. Needs multiple visits, tests, reexamination, and time to make a proper diagnosis.
You bet, see often. Tough diagnosis for many docs, even neurologists. So, need to assure you do not have arteritis or vasculitis, lupus, anti-phospholipid antibody syndrome, Lyme disease, maybe HIV or syphilis, vitamin B-12 deficiency, CADASIL, and perhaps a few rare disorders in addition. MS should be a POSITIVE confirmed diagnosis, not a diagnosis of EXCLUSION.