What Causes Persistent Pain In The Ankle?

i am a 38 yr old female with recurring ankle pain on the front top of the ankle for the last three weeks. i have had an x-ray which showed nothing, and a second doctor claimed i had ruptured something or other and to rest. rest certainly makes the ankle feel better, but walking or any type of exercise produces pain. i am having difficulty walking with my foot flat to the floor as this is painful, and therefore am walking on the side of the foot, causing other pains. please help