Anything that increases blood flow to the skin will heighten redness, and running will
certainly do that.
I think you do indeed have seborrheic dermatitis
, which will
, certainly go away, though you may have to treat it from time to time. Try the ketoconazole cream for a couple of weeks regularly. If that doesn't help enough, ask your doctor to consider a mild but prescription-strength topical steroid for intermittent use. Another option would be the non-steroids Protopic or Elidel.