My older daughter complained of that a while back. I thought it was odd and I checked her scalp. She had a couple of super-dry areas on her scalp where the skin was getting almost crusty. I could see how it would hurt! Anyhow, I bought her Head & Shoulders, which she uses every other time she washes her hair, and Aveda Dry Remedy, which she uses on alternating times. The combination of a super-hydrating shampoo/conditioner plus the shampoo that gets rid of the super dry skin seems to help her scalp. She says it doesn't hurt anymore. I don't know if this may be what's happening to you, but I thought I'd throw it out there. Another thought is maybe your scalp is irritated due to heat styling or chemicals from styling products? I have a friend who actually became allergic to an ingredient in her hair dye (what a bummer, huh?). Now she can only use henna-based dyes. Could be that you're just developing some kind of sensitivity?