I like using the flag in the background. I don't feel it screams punk rock however. I imagine something with lots of black, girls with pink hair and billions of lines of text about the lame concert.
Im by no means an expert ! but try Making the text alot larger, more busting out of the picture. Id also angle the oil paintings and make it look as if they are glued up or pinned to flag. Then id try to make the paintings look a little more punky' then just adding a guitar, Try to put some tattoo's and Rough edge character to it !
hope this helps !