Constantly sunbruned

So im extreamly light skined. No matter how many times i apply sunscreen. No matter how high my sunscreen is. I always get burned. Ive tried diffrent brands. Diffrent SPF's. Ive even gone as far as applying every 10-20 minutes. Ive always gotten burned. Badly. This is one of the worst burns ive ever had. Ive got blisters. And i cant wear any kind of clothing. Even silk hurts. Everything hurts. And is nearly unbearable... Please help.. I need it gone asap. And it needs to stop hurting... Please help....