I agree with Diana. The best thing you can do right now for it is to avoid the sun! I know how you feel it is sooo painful. In the meantime, try using a sulfate shampoo like the Carols Daughter Monoi Repairing Shampoo. It contains soothing oats and is extremely gentle on the scalp and hair.
Also, remember to keep your hair and scalp extra hydrated to prevent flaking and dryness.
Monoi Repairing Hair Mask