You`re not the only one. I also have got this attitude changes like manic and depressed, and bite my nails and the skin around it. But I enjoy destroying myself so that` not such a big problem for me. I can`t tell you what 2 do. If you don`t do anything, you`ll get used 2 it.
My stupidity started when I was 13. And I`m 17 know. But I`ve been drinking a lot so that may have caused some problems.
Maybe you should talk 2 a specialist if it`s not a problem because mood changes can and don`t have to be related 2 puberty.. But if they are regular... hm... you should talk to specialist.
You picking your hair can be some sort of habit. And when we`ve got that, it can be really hard to get rid of it. Try to remind yourself every time you unconsciously do that, that you don`t want to. Maybe you`ll have some ups and downs, but that`s usual.
If u have some irresistible urge or something, try 2 talk 2 specialist. If u care about yourself, you`ll do so. He can b sure what is happening 2 you. It doesn`t mean you r crazy or something. u shouldn`t b ashamed of that because "normal" is relative concept...
Everything is gonna be ok. You just have to want it and do something about it. It depends on you...
Have you read MedHelp information(definition, symptoms, posts, discussions)? This might help you.
http://www.medhelp.org/tags/show/12990/Bipolar-Disorder
http://www.medhelp.org/medical-information/show/410/Obsessive-compulsive-disorder
http://www.medhelp.org/search/expanded?cat=posts&query=OCD
Good luck... If I can help you somehow, feel free to ask...