I can't figure out why it's hurting or how i might have injured it. It's very annoying.
I know how i got the scratch on my arm, i ran into something pointy while walking around my desk this morning when i got to work. However i was kind of tired at the time and although i vaguely remember the moment when i got scratched scratched, i didn't stop to look at it till i was sitting down, and at that point i couldn't figure out exactly what it was i'd bumped into.
Just my day for being injured i guess =P