It's not uncommon to feel that way towards the end of chemo. I think it's to do with coming towards the end of such intense treatment. I was managing more or less okay until the end of chemo and then I pretty much fell apart overnight. I managed finally to get in to see a psychologist and had about half a dozen appointments over the next few months which helped me get my head above water again. If you're not already seeing a psychologist or counsellor it may well be time to think about it. You can access a mental health care plan through your GP.