I felt exactly the same way but after my second round of chemo. It is definitely the combination of all of the drugs. I saw the psychologist at the hospital and honestly it was the best thing I ever did. I am normally quite introverted but boy did it feel good to let someone really know how I was feeling and coping. He also put me on to meditation/ relaxation techniques. This worked wonders for me. Don't feel you need to do it on your own. There are lots of professionals willing to help .
Good luck with your next round!