I'm a runner and started having shin pain. there's a large indent along my tibia (medial) with a lump to the side of it. sound like a stress fracture?

Possible: But i'm having a real hard time with your description telling if the indent is on the bone or in the muscle area. You could have a fascial defect as well that is causing pain in the same area. At any rate, it should be looked at by a doctor because the treatment for the stress fracture would be rest while the treatment for the other defect would be therapy.

No: Stress fractures present with pain but not with large indents along the tibia. The fractures are usually only seen on xrays and are usually very small on the order of millimeters. If you had a large indented fracture on your tibia you would likely not be able to walk. For persistent leg pain, seeing an md for evaluation is warranted.