just thought of one more thing, is there a history of thyroid problems in your family? Hasimotos tends to be hereditay and cause many symptoms you mentioned, this can be determined through a tsh panel.
been tested for mono??? your doctor should do a cbc on you.
It is impossible for me to say if your issue may be precipitated by psychological or physical issues, because a medical illness can manifest itself in loss of energy and depressed mood, just as emotional problems such as depression can manifest in physical symptoms. As Cherie762 is suggesting, if you haven't already, you should go to your primary care physician first for a medical workup. I will add one question to ask yourself: did anything happen in your life a month ago that you would consider significant? Breakup with a significant other, anniversary of some type, etc.? If the answer if yes, then it may be an emotional reaction to something you've experienced. Regardless, I would suggest that you first see your primary doctor.