Fear of crowds, claustrophobia at rock concert treatment ideas?

Hang back. Practically every rock concert has an area to chill out, away from the stage and the pushy concert-goers, but within earshot of the music. If you are not afraid of heights, try the last row of seats in the balcony, near an exit and usually pretty open. Avoid drinking or getting high, since a loss of control might precipitate anxiety. Chill out, enjoy the music and leave before/during the encore.
Treatment ideas. Learn and practice coping skills first, then gradually expose to the fear situation. For example, starting with a smaller crowds, brief period of time, and gradually increase to bigger crowds, longer period of time.