Pain in thigh and leg

Patient: Im suffering server pain in my left leg from top to toe, it is so bad that is reducing me to tears ….. it starts at the top of the back of my thigh and goes right down to the knee then down to my foot .. it is a real sharp pain it is also causing pain spasms and it is hard to sit down and to straighten my leg, or even stand on the heel of my foot and im finding it hard to do anything at all cause of the pain