Can you remember when this started happening? I would suggest looking back to see when it started, and examining things that happened around that time that could have caused this. Perhaps you already know of an event that made you feel terrible, but from what you wrote it looks like you do not. Maybe you are subconsciously preoccupied with something, so try digging deep to find out what it could be. If you know what it is that's bothering you, you can work toward resolving the issue. I can't tell help you to resolve said issue without knowing what it is. Still, the first step is acknowledging the problem, and then working towards fixing it. If it's really just you being overly worried or anxious about things in your life, maybe you should try talking to a parent, friend, or some other trusted person about it. Getting these these things off your chest can really help, plus you get a fresh perspective on it.
Perhaps if it's really serious you may consider getting professional help, but only if you think you need it and I would talk to an adult before deciding that. If it goes on for over two weeks then maybe start considering it.
-Mary
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I happen to think you're pretty dandy.