Once in awhile I'll get a small patch of really dry skin which causes scalp itch. It's about the size of a quarter, above my right eye, right at the hairline and behind it. I have a feeling it may be due to my facial skincare products penetrating the hairline.
There are various different reasons for this condition.
Dandruff - Flaky, dry skin due to overactive oil glands which causes the scalp to shed dead skin cells faster. A buildup of this dead skin causes an itch. You could have Seborrheic Dermatitis, which is another name for excessive dandruff, (called cradle cap in babies). Most people will experience dandruff at some point in their lives.
To combat dandruff, I have previously used a medicated tar shampoo with good results. This shampoo must be left on the head long enough for the active ingredient to penetrate, at least five minutes. This is typically the most common treatment for this condition. It seems to be a little stronger than your typical dandruff shampoo, it costs just a bit more and it eliminated the problem I was having. Topical lotions are also commonly used.
Mild cases of scalp itch can be attributed to things like our work environment. If things like dust or harsh weather are present, these in addition to numerous other factors could be the reason for this discomfort.
Some other causes include stress and anxiety, a vitamin deficiency, allergies and something as simple as not rinsing your hair well enough after shampooing. Some say to use cool water to rinse, and that may help.
Yet another possibility is that the shampoo you use could contain chemicals your system is sensitive to like Sodium Laureth Sulfate (SLS), Formaldehyde, Parabens and Silicon. Sodium Chloride (a.k.a. table salt) is used as a thickener in some shampoos. It could also be causing dryness.
You also may suffer with Scalp Psoriasis - a skin disorder that can also affect the joints.
Don't rule out the ringworm, either. It is a fungal infection caused by dermatophytes which can spread aggressively and contagiously, resulting in permanent hair loss if left untreated.
Other causes with varying ranges of severity exist, so it's important to see a doctor or dermatologist if your condition is severe.