Can taking Comuadin 5mg make you tired?

My doctor recently put me on comuadin after having a cardioversion and a pacemaker put in. I'm so tired all the time,,it's been 5 weeks. I may be just run down,,as I had an operation (hydracele) in Nov. then a super cold virus that lasted 3 mons. I have been walking every two days to get my energy back. I'm thinking it's the comuadin