Problem: Losing weight From Legs too fast

Hi everyone, ever since I started eating more vegetables and walking more three weeks ago, I started rapidly losing weight. Most of the weight is coming off from my thighs and legs but not so much upper body. I think my upper body weight is heavy for my my legs to carry and is resulting in back problems. What should I do? I know you cant target body fat, but will this end up in me being in a wheel chair? lol?