Just go see a psychiatrist and tell them about what you're feeling. As MDs, they know what tests to run to screen you for low-hanging physiological fruit like

Just go see a psychiatrist and tell them about what you're feeling. As MDs, they know what tests to run to screen you for low-hanging physiological fruit like anemia or hypothyroidism. There's probably over a 50% chance you have at least one of them and this is the most straightforward way to rule them out. And if they rule out those, then they're equipped to check if you have depression or something. "Exercising a lot" could also be a potential source, depending on what you mean. You might be exercising so much that your fatigue is accumulating faster than you can dissipate it with your available recovery sources. Experimenting with a deload week every 4-8 weeks where you do half the volume and half the intensity might be worth trying. A sleep study might also be worth investigating. You might have sleep apnea and not know it.