It could be your body making more white cells to combat disease resistance. Mine plummeted after chemo and I ended up with a cold that lasted 3 flaming months lol. The cells are made in the long bones of your body so the aches are kind of a good thing although its not great to have at the time. I am on Tamoxifen which I think messes with things as well as my knees and hips often ache especially in bed. I have noticed if I go for a long walk, its tight as for a start and about half way it starts going away so keep up the exercise even though you don't want to.