I get terrible throbbing headaches a few hours after running (just a few km), but not after aerobic style cardio workouts. what kind of doctor should i see about this? thanks.

Any doctor: could evaluate you for this, but first try drinking a full glass of liquid before, during and immediately after a run. This could all be just dehydration. If you can get a drink containing electrolytes (sodium, potassium, magnesium) it will stay with you longer and help more.

Can't be exact about: The cause of headaches because there are several major types, e.g., vascular, sinus, muscular, tension, etc. Please see you family doc so he/she can examine you and give you the proper treatment for the type of headache you have. Sorry if you are dealing w/this. Peace and good health.