For the past few days ive been experiencing lower back pain but today it is focusing on my lower left side and i can feel it moving down the left side of my thigh. what could this be?

Pain with radiation : Pain in the lower back region that radiates to the lower extremity area would need to be evaluated by your doctor. The possibilities could include a herniated disc in the lumbar region of your back or a kidney stone or some other lesion that has caused a nerve to be irritated. Your doctor will need to evaluate all options.

Considerations: Although you could possess a disc compressing a nerve root, the anatomy of your description may implicate a superficial sensory nerve, lateral femoral cutaneous nerve of the thigh. An exam by your doctor can sort this out.