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I think it's related to the injuries before (at least the pain that's in that leg) often ligaments don't heal properly, and if you're as active as you say you are the impact of running, jumping etc would definately strain it.
Now that it's in both legs that leads me to think either it's pyschological ie imagination which is not uncommon for people like when women want to get pregnant really badly often they end up with physical symptoms of pregnancy because they hope for it so much.
Or two there is something else going on. Something related to the impact on the joints when you play sports or something as serious as blood clots (not saying that's what it is but you just don't know).
So do go to a doctor - and explain everything, all the details and how often the pain occurs, keep a diary of when the pain happens (ie date and time) and see if there is a pattern to the sharp pains (like right after playing sports). But do go to a doctor. It could be something simple and fixable and then you wouldn't have to deal with the pain anymore.