Tut tut, Louise
Try the usual aftersun, and if that doesnt work, try camomile lotion.
Another good tip is to get a ice cold face cloth, and stick it round your wrists and behind your ears. Those are pulse points, and it cools you down quicker, also try sticking one bhind your kness.
I know how nasty sunburn can be - i went to australia, and went to the beach and came back with 2nd degree burns and blisters the size of small plates!!!
Hope you is ok soon
Heat
xxx