My Dad Recently Had A Triple Bypass. 2weeks Ago. He

My dad recently had a triple bypass. 2weeks ago. He just came home and is extremely weak and fatigued. It takes about ten minutes, in short movements to get up. He walks about 40 paces and is wiped out, totally winded and complains about his legs hurt. He has to sit about 15 min to continue his walk to his bathroom. His blood pressure readings have been 84/47 for a few days. Is this a concern? I don't know what to expect during recovery.