Red rash/blotches along hairline.

For the past few years I've had problems with my scalp itching, and dandruff. It seems to be worse in the summer, and also worse after showers.
I also have dandruff in my eyebrows sometimes.

Occasionally (like today) I'll notice a rash along my hairline of red areas, which itch and are slightly raised. It all seems to be at the front of my scalp, in the forehead and temple areas.

I use dandruff shampoo but it doesn't seem to help (and as I said, it is worse after showers) so I don't know if I'm reacting to the shampoo or if this is some other skin condition.

I've been doing some reading on skin conditions, but most of the things that seem to match up aren't located solely on the scalp.

Any idea what it might be?