I don't know why I'm like this?!

I don't know why I'm like this?

I'm 16, almost 17. I sleep about 10 hours a night and eat healthily. During the day, I always feel tired and worn out, even if I haven't done anything to provoke this. Also, I've became very irritable, and I find the slightest things very annoying and tend to yell for no reason. Some days I feel really 'teary' and want to cry at a lot of things that don't usually bother me.
Any ideas on why I'm like this?
Thanks in advance!

Well, you have a lot of wonderful things on your side.... first, you are young, you sound like you get plenty of rest, and you say you eat healthily. There are many reasons why you might be feeling a little irritable, annoyed, and emotional. I have a couple of questions for you though. How long has this been happening? Are you on any medications? Have you experienced any "drama" in your life recently? (a relationship gone bad, divorce of parents, moved to a different home, etc. ???) These symptoms could be caused by a hormonal imbalance, depression, thyroid problem etc. The best thing for you to do at this time is to go and have a visit along with blood work with your family physician. He/she can direct you to the appropriate help after careful consideration of your symptoms. Please seek medical attention as soon as possible so that you can get back on track! You have recognized that these new symptoms are not normal for you. Has anyone else mentioned that they have noticed a change in your personality recently? Good luck!