I run about 20 miles a week and do other activities (ongoing for about 3 years). About 3 months ago, w/out any apparent cause, I developed pain in the outside of my left ankle. At first it would come in the morning and later go away. Later it was only after running. Now it arrives during running and is in the general area of the outer ankle, top of foot, and inside of heel. The only movement that consistently reproduces the pain is hopping on the left foot or climbing stairs (i.e. not during walking, balancing on one foot, raising up on the toes, or going down stairs). It is also possible to run up on my toes w/out pain, but typical heel-toe running causes the intermittent pain.

My doctor saw nothing wrong on the x ray and ordered an MRI, which I am doing tomorrow. He said he suspects a "stress injury". However nothing I have read on the internet about stress fractures specifically describes my symptoms. I have no swelling, no specific spot of pain that can be touched, no discoloration, and a fairly low but inhibiting level of pain. Also stress fractures seem to occur in the metarsal (top of foot?) bones, which is not where I am having the problem.

What else could this be other than a stress fracture? What can I do to cure this problem (and keep running)?