high pulse rate with times of hypertension and hypotension

I had double bypass surg in 2007 and have had no problems since until possibly now. I can walk at a good pace on treadmill or up and down hills with no problem which is how I found out my problem in 2007. But this week I have been lightheaded and weak with legs feeling rubbbery. My blood pressure last night was like 110/64 and pulse rate 64. Then later that night it was 99/54 but pulse rate about same. Then later in the middle of the night was still low like before but pulse rate was 106. T hen the next morning bp was like 106/74 with  pulse rate 101. Then mid morning BP was 132/ 89 with pulse rate 159. Now my BP is 116/64 and pulse rate is 88. What is going on and should Imove my April appt with cardiologist up?  I took a 5mg lisinopril about 2 hours ago.