I got a sunburn 3 days ago and now I itch worse than ever. What do I do?

I am a fair skinned red head, I sunburn a lot I'm used to burning for a few days pealing and being done. I have never experienced anything like this. I haven't slept the past two nights because I itch so bad (mainly my back and stomach). If I scratch it hurts, if I don't the itch drives me crazy to the point I twitch. I don't know what to do because I have been applying aloe and after sun moisturizers, I have taken hot showers, I've taken cold showers, and even tried using cold wet rags but I still itch.... What's going on?! And to top it all off I sunburned my left knee and it feels at points like I have icy hot on it, I can deal with that though, it's the itching that's driving me crazy! What can I do?!?!?!?!