What are some things that cause outer ankle pain?

Tear of...: First degree sprain - is a tear of only a few fibers of the ligament (in this case, the anterior-tibial fibular ligament) the atfl. It's also known as a "strain" and caused from a rapid inversion injury of the ankle or "rolling" the ankle inside, such as stepping off a curb the wrong way.

Sprained ligaments: Or tendonopathy to the peroneal tendons, or irritation of the sural nerve. Type of pain with aggravating factors can help narrow diagnosis.

Depends: There are too many sources of ankle to pain list here. The treatment and the ability to control it would depend on an accurate diagnosis and workup. See a foot and ankle specialist for the right plan.