What 's the 3rd degree sunburn?

It would have to be one hell of a sunburn to be 3rd degree. That involves charring of the skin and destruction of the nerve endings. You would have spent some time in a burn unit. As an EMT, I have never seen a 3rd degree sunburn.

Most sever sunburns are 2nd degree (blistering, extreme pain and peeling).

I'm assuming the burn is healed. If it is, you can apply vitamin E cream to it and that might reduce the scarring. Unfortunately, burn scars of any kind are very hard-if not impossible-to ger rid of completely. The scars might fade over time but it could take months, if not years.

You need to stay out of the sun. Going back out will only worsen the scarring. Scars are very sensitive to sunlight and the sun can actually cause the scarring to spread.

I have some scars on my stomach and chest from a severe 2nd degree sunburn 3 years ago. They have faded but they are still there. I had a burn surface area of about 22% that 2nd degree. Ouch. I no longer sunbathe and when I'm out in the sun for more than 30 minutes or so, I apply a sunscreen of at least 60 SPF. It's not worth the pain to go without sunscreen. See product about treatment sunburn continue.