I'm sorry you haven't been feeling well. It's good that you've got a doctor's appointment to get checked out.
This could be a number of things, from a low grade infection, to a virus that's lingering, to allergies, to an autoimmune disease such as lup
us (one of my first symptoms of lup
us and one that continues to "tell" me when I'm having a flare is a lingering sore throat
and extreme fatigue with no other known cause)
During these times, do you run any fever? Any nausea/vomiting?