Bipolar and anxiety

So, I'm pretty sure I have a bipolar disorder. For a few days at a time, 5 days for example, I feel so full of energy and confident. I feel energetic and like I can do anything. After then I go into a depression and I don't feel like doing anything, I feel worthless and unworthy of having friends, and I wonder the point of living if you die anyways. But I also get so anxious around other people I'm too afraid to tell anyone. I have a little online diary where no one knows who I am and that's the only place a express how I feel. Im too afraid to tell even my mom because I feel like I'm just another problem for her to deal with (my brother has anxiety and ADHD). I'm always afraid of being judged by others and I don't open up to anyone. I'm 13 years old so I can't just drive to my doctor or anything. I don't know if it's normal to feel like this but from looking up symptoms online I have almost every one of them for social anxiety and bipolar. I also have some bad stomach issues where a couple times a day I'll just have these crippling stomach aches that almost spread up to my chest. The depression part has been getting worse lately and so has the stomach pain. I'm also so tired at school I feel like I might faint, no matter how much sleep I get. Help?