Guinness -
I have the same thing going on right now - your description sounds like it fits almost to a T.
It could be just about anything - there are all sorts of muscles, nerves, tendons and joints in play with your leg, and if any one small thing gets even slightly out of whack (or even your lower back), it can set in motion a whole series of events, all of which bring different sensations, discomfort, etc.
It is not anything ominous. Especially **S - any neuro will tell you, as mine did, that this type of pain/discomfort/parasthesias presentation is just not consistent with that disorder. And MS? I hardly think so - this just isn't how that disease presents itself, typically, and the fact that you're not overwhelmingly disabled at this point (given that your leg would be the focal area) leads me to doubt this is some MS exacerbation.
You are going through something a lot of us are/have going through. None of us has been diagnosed with a serious illness, and no one has dropped dead. Let yourself be at ease.
All the best -
JG