I have fallen down stairs before, not fun, really sorry to hear about the weakness in your leg. If there is a silver lining it is that you didnt break a bone and now know that this is something to watch out for.

I use a cane for short trips, in and out of a convienence store, that sort of thing.
Otherwise I use a walker or forearm crutches. Personally I prefer the walker because I can sit on it or set stuff on it, crutches are just a hassle, but sometimes they work better.

At work I use a Wheelchair, but I have been trying to stand up and move around without it (with my walker) at least once a week.

Recently I put my third floor condo on the market and moved into a ground floor apartment, because of the fear of falls down the stairs, especially in the winter when the stairs are covered in snow or ice.

Sometimes even my rolling walker doesnt feel stable enough, I have a tendency to list to the sides of it if I am not careful and can feel it tipping.

I hope the fall doesnt cause any hidden problems, but I would definitely let a doc know ASAP, that this is an issue.