Hi, thanks for posting your query
It seems you had a severe sunburn reaction which is characterized by pain, swelling, dizziness
, nausea and fever in addition to redness and burning .
To treat the same
Do cold compresses over the burnt area and frequent cold
Apply cold Aloe vera gel
You may apply hydrocortisone cream
Avoid further sun exposure till it heals.
Drink plenty of water
Take oral beta carotene
Though you used a sunscreen but you need to use it as follows:
Apply sunscreen about 30 minutes before you go outside.
Repeat every 3 -4 hours.
Apply liberal amount that is about 1 ounce each time .
It should cover both UVA and UVB rays.
If the symptoms worsen you should immediately contact your dermatologist
Hope this helps you
wish you a speedy recovery