Haha I'm 18. I have the same exact thing you have!
You need to be confident. You have anxiety and anxiety attacks, which are medical conditions that CAN be treated if you take proper action. Every day I feel as though something is wrong with me, usually it's something new because after I find out that nothing is wrong I feel a bit better. As you learn how to cope with anxiety you'll see improvements in your symptoms and they will eventually fade away. But you need to get help from someone who's willing to listen.
1. Get a counselor. Most counties have mental health buildings where you can speak to someone who can give you advice and teach you how to face your fears. Your fear may be strong but when your mind knows how to fight that fear and dispel it quickly you'll see improvement.
2. I know what it's like to have anxiety attacks and yeah, they blow. It's like you're feeling like yourself one minute and the next you are feeling like crap and you know you shouldn't have to but your mind keeps going at a mile a minute.
3. Whenever you start having hypochondriac-like thoughts, sit down, take some deep breaths and think of a chalk board. Each thought that comes to your mind goes on that chalk board, but before you can even get into that thought, erase it with the eraser. Keep focused on erasing those thoughts with your "eraser".
4. You have to understand that you will have good days, and you will have good days that go bad. That's a really good thing. That means you're making progression from the bad to good. Over time you'll notice that the amount of time you're doing good will highly outweigh the bad and will eventually fizzle out over time.
5. Depressive moods are common during anxiety. Do not think you're going back into a slump.. you're not. It's just that built up frustration controlling your emotions. Take a nap or do something you usually enjoy to get your mind off things...
Hope this did something for you.