it looks like u accidentally used the fill tool... um, try undoing it or break out the eraser and clean it up.. that's all i can think of

Actually the best way to fill in those spaces is to place another layer beneath this and paint the black, then if you go over your original lines to come back and erase it. You have more than enough space. Try it, clean this up and you'll see.

OR... just avoid the fill tool. It's the tool of the devil you know.
Layers. They'll be your best friend.... friend.