What Causes Constant Stinging And Pain On Sunburn?

I got extremley sunburt three days ago. So bad that everytime i try to walk i end up screaming in pain and collapsing. I cannot sleep and have constant pain and stinging. Ive done everything you are supposed to do to treat a pain and have taken pain relivers, numbing and soothing creams and gels. What do i do? I cant handle it anymore