what happened today

I was practicing for my English competition today, as usual. But, there's something weird today that I can't explain...

I don't know what a thing that I've been thinking of. I'm just worried and worried, but I don't know what am I worried about. It's confusing. Today actually I had a good day, but there's just something dark, something strange, weird, and I can't explain it why. I am confused.

do you guys know what kind of feeling is this? I've never felt this before. Help?