Sunburn needs to be treated like a thermal burn.
If the skin is just red, then after sun lotion is fine.
If there is blistering, then proessional advice is needed.
Some will treat by exposure, others will dress the bisters, which some may deroof.
Get better soon!
Burnt skin is less resistant to UV than unburnt skin, so use an effective sunblock, or keep cllothed, when out for at least the next 12 months.