Obviously it is best to check with a doctor as you are doing.
I have been dealing with this same issue for a long time before and after sobriety.
I get fatigued all the time still too and I am 5 months sober next week. For me I think I expected to have all this extra energy because I am sober. I found out that is not the case.
I don't think drinking was the cause of my oversleeping, laying in bed, and feeling tired. I am finding out that my diet, exercise, and activities are really the cause.
As quit mentioned caffeine is a big one too. I stopped my high caffeine intake and quit drinking sugary drinks. I stopped eating fast food, fried foods, processed foods, huge meals, and added nuts, fruits, veggies, and lots of water to my diet.
It is not the most exciting lifestyle but I feel better throughout the day, have much more energy, and I sleep less which allows me to get more done. After I really stuck on my diet I started jumping right out of bed too. I used to sleep 10-12 hours a night but now I go 7. And I have more energy than ever. It is hard to stick too though, and when I start slipping I am right back to sleeping more and fatigue.
Best of luck