I have a blister on the ball of my foot, help?

I've been playing HvZ(Humans vs Zombies) for the past two days, and the game isn't going to end for another 3. The only shoes I have besides flats and flip flops are my converse. Obviously, they aren't the best shoes when it comes to support for your feet when running.

Long story short, they caused me to have a huge blister on my right foot. Is there anything I can do to help it stop hurting so bad? I have to be on my feet for the next 3 days for about 7-8 hours a day, so staying off of it isn't an option.

Please only serious answers. Thank you! (: