Anxiety is an equal opportunity invader, will settle anywhere, but really originates in the brain, as far as I know.
You need your legs to be strong and supportive. So try some leg strengthening exercises to let the brain know you are not giving in to this. In the gym there are a number of machines that focus on lower body. The leg press is one. Maybe try YT, maybe some leg weights, or just walking. Do consider what you want to do to contain the anxiety. A therapist? Wishing you all the best, keep us posted.