Hayley, It could just be tiredness catching up with you. I know I didn't sleep well and actually had insomnia through all of my treatment but later I had really a few months when I was just flat out exhausted all the time. I also had problems with anemia for quite a while. As David mentioned, it could also be your thyroid--you should probably get a blood test for that just to be sure it hasn't already quit on you.
Nelie