I Occasionally Have Foot Drop But It Is Not Constant.

I occasionally have foot drop but it is not constant. I also have numb toes on the opposite foot. And I have trouble with my legs being extremely heavy which makes it hard to walk but that's not a constant either. I'm 59 years old, I have had the test where they take blood pressures on my legs and that was fine. I've had US on my legs to check for blood clots mostly because I've had a high d-dimer twice all normal. What do you suggest?