I take 50 mg Atenolol 1/day in the morning, and my BP is usually pretty close to normal. Today, due to stress, it spiked to 180/110, so I took a second dose at midday. It went down to 160/90 after resting. Now, early evening, it's back up to 168/100. High BP gives me a splitting headache. Can I take a third dose now? Or is there something else I can try?