A clear or negative LP result does not mean you do not have MS. If the neuro is basing the diagnosis on this test alone, RUN. You definitely need a second opinion. I do not know where you live, but check with you local MS society or association for a referral. There are neurologists and there are neurologists who deal with MS.
Now, what you describe may be something other than MS. You could be dealing with CFS (Chronic Fatigue). Until you have been seen by a qualified neurologist who deals with MS and have had all the tests, I would not opine as to what you may or may not have.
Of MS patients who get LPs, only 85% are positive for indicators for MS. Statistics do not tell us how many actually get a LP. I have had 2 LPs in my life, 1982 and again in 2002. Both LPs were negative. There is not one single test to determine whether or not you have MS.
The good news, there are many neurologists available who can provide you with a diagnosis. I will keep you in my prayers.