There are a number of illnesses that can cause the symptoms you are describing such as ME or Lyme disease. There are also other more dramatic possibilities that

There are a number of illnesses that can cause the symptoms you are describing such as ME or Lyme disease. There are also other more dramatic possibilities that are more unlikely as I assume you are reasonably young. It is also possible you have developed an illness like depression or dysthymia. It is possible that the strain of the previous few years has caused this to manifest somehow. I also recently read an article about sleep apnea which can cause chronic fatigue like symptoms. Some people don't know they have it because they don't store the memories of waking up; often it is their partners who prompt them to seek medical help. Do you share your bed with anyone? Have they noticed anything strange about your sleep habit? A sleep study might reveal something you weren't expecting. But for sure, the first thing to do is to just talk this over with an actual doctor and not a computer programmer (me) who likes to read Wikipedia for fun.