What Causes Pain In The Hip Which Radiates Up To The Leg?

i have feeling pain in my right leg from starting joint of hip through out in my leg, doctor said to me that your disc is prolapse, and he refered to orthopadic doctor given me the oppointment on 11th of april. i want to know what is actual problem , i dnt have pain in my back, but as per doctor it is happened due to the bavk disc problem