Sleep apnea?!

Sleep apnea?

I'm overweight and im 15 years old. For the past 3 months ive been experiencing fatique during the day and decreased concentration. I went to the doctor and he found nothing wrong. He told me to exersise and cut down. I havent had any caffeine in 3 months. I went to the doctor about a month ago. I started walking today. I went around the block twice. I'm not sure whats causing it. I notice that i go to bed really late and get up later in the day. I sleep 9 hours and still feel sleepy.

I need some advice besides seeing the doctor for this? How can I sleep better at night?

1 week ago
These spells come and go. I can have fatique for as long as 5 days and then it goes away for a few days and comes back.

it is possible that you are getting to much sleep. Sometimes that will throw your body's timing off and make you feel tired.
Do you snore? You could be waking yourself up and not even know it. This will create disturbed sleep (similar to sleep apnea) causing the tired sensation all day long.
Another factor could just be your age. You are maturing and your hormones are out of control. Sorry to be the bearer of bad news but it could be many, many things