MY Husband Started Pms-Carvedilol 12.5mg. Yesterday.This A.m. Woke Up Lightheaded

MY husband started Pms-Carvedilol 12.5mg. yesterday.This a.m. woke up lightheaded and dizzy, took his a.m. dose with breakfast. Later in a.m. had a terrible headache . I gave him Tylenol 500 mg. After lunch had a nap and seems better. Previously had been on Pms- Metoprolol-L50 mg. b.i.d.He is 88 years old, has a pacemaker.Diagnosed with cardiac failure 1 1/2 years ago. He also has renal failure, controlled with diet at present