Key to know if you were on road bars or aero bars. In either case, there are areas where you can put key nerves under serious pressure. The heel of your hand is a bad area for prolonged pressure which you can get from a long ride on road bars. Those same nerves come through the elbow area and can be put under pressure by certain aerobar armrests/positions. Sometimes subtle changes can relieve the symptoms. The classic thing most folks will tell you if you’re riding a standard road bike is to figure out how to reduce the percentage of your body weight being carried by your hands. Sometimes this is as simple as moving the nose of the saddle up a bit. With aerobars, experiment with moving pads forward or back, and consider aftermarket pads like CeeGees that offer more cushion.