Recently I had a problem with my spine .The soft tissue moved and I felt the weight on my feet .I went  to the physio it solved the problem but some times if I stand im feeling very stiffness in my legs also heavy it will go by sitting or lying down.Is it related to disc problem or something else?
Definitely this problem can be due to a pressure by disc prolapse. You should go for an X-Ray of lumbosacral vertebrae in lateral as well as A. P views to find if there is any reduction in the intervertebral spaces or any other signs of pressure on the nerve roots or spinal cord itself.In the meantime you should use a lumbosacral belt particularly while travelling or doing exertional work.