Foot drop symptoms

[zejoao1]

Over the past few months I've been having an on-and-off problem with my left foot. Initially and over the course of a few months, it would only happen occasionally: it felt like I could not control my foot properly when walking and it would weirdly tilt to the left, as if I could not keep it straight when lifting it. At the time I didn't give it too much importance, because it was quite rare.

I'm a reasonably active person, so I continued doing my normal activity: cycle to work every day, play football, run, go to the gym, do trekking.
Now recently, since about 3 weeks ago, the problem got a lot worse and more frequent. I cannot walk normally without the external part of my foot dragging on the floor. If I concentrate and walk slowly, I can forcefully keep the foot somewhat straight, but if I do it for a while, my foot and leg get really tired and sore, so this is not something I can just start doing every time I walk.

I could never notice this problem while exercising / running, it's always when walking.

Before you tell me to go see a doctor, I have been and have my next appointment scheduled, but this is a rather slow process and I can't see it evolving. My orthopedist says everything looks normal: no loss of muscle strength anywhere (I can completely control my foot and pass all the tests when in rest), had nerve conduction studies which were also normal, can walk on my toes and on my heels, etc. Babinski test is also not positive.
As far as I can remember there was no significant trauma to this leg, other than normal contact when playing football.
I also sometimes feel a slight numbness in the lower leg and foot when seated. I should also add that this condition hasn't been painful so far.

Over this period I've had 3 episodes of my left knee giving way and getting really painful for the subsequent hours, but my orthopedist and GP tell me it should not be related (which I find suspicious).

I would like to know if anyone experienced (or know someone who did) something similar and know what this is or what kind of exercises I could do to improve this problem (I'm hopping there's some kind of physical treatment I can do to improve this).

Thanks.