How can i tell if factored my ankle?

There are rules: There is a set of rules called the Ottawa ankle rules that doctors use to determine if you need an X-ray. If any of these 3 things is present, you need an X-ray: Tenderness to touch on the back edge of the bottom 3 inches of each ankle knob. (that's 2) Inability to walk 4 steps. If you have any of these, you need an X-ray.

Tender at the back: Ankle sprains tend to be painful to touch over the front of the ankle bones while fractures are more likely to hurt pressure is applied to the back of the bones. Also, if you're able to walk (albeit with a limp) it's highly unlikely that it is fractured.