How long does sunburn itch last?!?

I managed to get a moderate sunburn 3 days ago and after having a cool shower yesterday afternoon the worst itch I have ever experienced in my life just suddenly started. It feels a bit better now but yesterday I was rubbing **** loads of aftersun lotion into my arms, twitching and almost crying. Took about half an hour for it to die down a little after I put a shirt on. I can still feel it a bit and I'm about to go get a shower again, I'm worried the itch from hell will come back afterwards! How long will this take to go away :(