Any family doctor, can refer you to the right specialist, after listening to your symptoms, feeling, tired, sleepy and lack of energy can be contributed by various disorders,
sleep apnea, thyroid, diabetes, adrenal fatigue, etc....
I suggest you visit a family doctor, to perform basic lab test, to rule out anything physical, you may even consult with a pyschiatrist, for an evaluation to rule out depression, stress etc... that can cause those very same symptoms.