I got cut pretty bad from sandpaper on my arm... I guess you'd say more like abraded, but it went fairly deep. Not deep enough to need stitches but deep enough to cause considerable bleeding and subsequent scabbing over. This was about a week ago, and now I'm having a strange pain in my arm, it's like a very deep pain, like way down in my muscle, radiating and almost electrical feeling. Is this related? Might I have some kind of infection, and if so, what kind of infection and is it too late to do anything about it? The sandpaper was new when it cut me, so it wasn't dirty... just regular old sandpaper.

It may not have been dirty, but it certainly was not sterile. Time to check in with your doctor.

Sounds like you may have some nerve damage

Seriously? I don't know if this is more mental than actually physical, so that's why I wanted to know if this pain is a real signal or could it be something else entirely, even just a mental thing because I've been worried about it, you know what I mean?

Get it checked out to be sure. Sandpaper is not sterile and carries germs, it could be infected.