Foot Blister Treatment?

My gym class was running today, and I usually wear my Vibram FiveFingers (barefoot shoes) to run in, but I didn't have them today, so I decided to run barefoot, thinking that the experience would be the same. For some reason, after running only half a mile, my feet were beginning to blister, and now (two hours later) I cannot walk on the balls of my feet because the pain is so bad. I have developing blisters about two inches in diameter on the balls of both feet, and I have to hobble around instead of walking, because I can't stand the sensation of anything touching the blisters. What should I do?