@ankara-- I'm not a doctor but it sounds like you might have a herniated disc in your back. I recognize the symptoms because I have it too.
When a spinal disc is herniated, spinal fluid leaks and applies pressure on the nerves. This causes pain in that area, and sometimes tingling or burning sensations in one of the legs. The burning sensation can also alternate between legs.
You need to get an MRI. This is the only way to know if you have a herniated disc. If you do, you will be given pain relievers, muscle relaxers and lower back pain exercises to relive the symptoms. I hope you will feel better soon!