I got a little nosebleed after an early run, very rare. 1 nostril, stopped after wiping. i've been congested lately, a little dehydrated. cause?

Nose bleed reasons:: nasal congestion or nasal dryness, ^ blood pressure, excessive use of decongestants, being at ^ altitude, trauma to nose, nose picking, or blowing the nose hard. Bacterial & viral infections can ^ risk as well as bleeding disorders. Recurrent nose bleeds may be due to broken vessel in the nose. Alcohol / cocaine abuse can cause nose bleeds, as can tumors.