What Causes Dry And Flaky Skin After A Partial Hysterectomy?

I had a partial hysterectomy 7 years ago. I still have my ovaries. I am now 40. My t-zone has always been extremely oily, suddenly, in the last few weeks, it is dry and flaky. I have a definite lack of energy in the afternoon and tend to have a general sense of "blah" in the early evenings. Like I don't want to go to bed, but I want to be home. I feel like I'm too young for this, but because I don't have periods, I don't know what my hormones are doing.