What Causes Shivering In Body While On Propranolol?

I am taking 20 mg once a day after about an hour I get so tired and don t care if I do anything. sometimes I get to shake and then I take 10 mg of propranolol. I had a bad two years financial. sometime if I make myself get up and go I am ok for about 5hours. I want to get off to see if that is the right thing. I have tried about three different meds. I am 84 and I suppose that does not help. I still have more energy than anyone from 70 on. I want to get back where I was. what do you say