Sun Burn Remedies?

My girlfriend Carmen and I are in Guatemala for a month, and then on to other countries. Carmen decided to go suntanning today, and even though she was wearing sunscreen, she still burnt pretty bad. She has fair skin to begin with, so a couple hours laying in the sun didn't do her any good. She is bright red, everywhere except where she was wearing a bikini. My back sort of burnt, but I have naturally darker skin then her to begin with, so it didn't get me too bad.

Anyone got any sun burn remedies of their own? She is in pain, and doesn't know what to do. Right now she is taking a cold shower to try to cool herself down. We have no aloe vera either at the moment.

Thanks.