my husband is taking 25 mg of metoprolol tartrate a day. he is on chemo, has cancer of the lungs and also COPD. three years ago he had triple bypass surgery and was put on this drug. However now his blood pressure readings are very low( 109/50, 96/55, 109/55, 124/65/ and today 98/53) and he is dizzy when first standing up, I am wondering if he really needs this drug??