Please, please be careful with this. As someone with blonde hair and blue eyes, I've got to tell you: I've had more than my share of sunburns, and they HURT!!!
I received radiation treatment this past winter, and started to get a nasty "sunburn" under the band of my bra. My radiation oncologist suggested, before trying anything prescription, that I use Aquaphor. It's thick-- almost like vaseline-- but it really did help. (So did going to work braless-- and I teach high school!!!-- but that's a different post altogether

)
I'm planning to bring some to WDW in 10 days, just in case!
It's Over The Counter; I got it at CVS.
Here's the lowdown according to google:
Aquaphor Healing Ointment
Advanced Healing for Dry, Cracked or Irritated Skin Aquaphor Healing Ointment protects dry, cracked or irritated skin to help enhance the natural healing process and restore smooth, healthy skin.
Clinically proven to reduce healing time
Creates a protective barrier that seals in moisture
Helps heal raw, irritated skin caused by radiation treatments, facial resurfacing procedures and Atopic Dermatitis
Soothes and helps protect extremely dry, chapped or chafed skin and lips caused by winter weather or diabetes
Soothes and protects minor burns
Fragrance-free, preservative-free, non-irritating
Eucerin Promise: High quality ingredients and clinically-proven formulas that help keep your skin healthy. Eucerin skin care is safe for sensitive skin and so effective that it's been trusted by dermatologists for years.