What Causes Elevated Blood Pressure In A Teenager?

My 17 year old son has had 3 episodes of extreme high blood pressure. The most resent was while at school and the school nurse had to call 911 because his bp was 190/130 and he was confused and felt faint. By the time he reached the hospital his bp had lowered without any meds to 170/100 and continued to come down on its own. Just as before all test, urine, and blood and EKG are normal. We are following up with our family doctor tomorrow, but don t feel at ease with the outcome so far. No energy drinks or substance abuse. There is strong family history of high blood pressure, but his spikes then goes back to normal. Is there anything specific I should have them further investigate?