weakness and fasiculations

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  I am a 39 yo healthy male distance runner. Normal diet, no vices. Had onset of twitching in legs 3 weeks ago (visible fasiculations)now in arms as well. Motor strength declined from running 10 miles easily to a few hundred yards over these three weeks. Weakness in arms is less severe. One week into the weakness I saw a neurologist who performed a "normal" EMG and routine blood work (ESR, CPK,TFT, aldolase Ca2+, etc) I did note a moderate URI one month ago. I am told no further tests are needed, but to come back in two months if not better. I am told it is unlikely to be ALS.
  I am a physician, but did not really get an explanation why an LP, MRI etc was not needed, nor why 2 months should elapse before a recheck.
  I was told this might be "post viral".
  Any thoughts?
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I suspect that the main thrust of the investigations was to differentiate between  post-viral fasiculations and ALS, if this is the case the LP and MRI would not have helped to differentiate the two problems, the EMG is very reasuring as by the time fasiculations are visible clinically in ALS there are other diagnostic abnormalities.
I suspect that the two month waiting period is to check that these fasiculationshave settled completely
which is a reasonable time period, either way the negative EMG is the key test.