I've had bumps (pimples) all over my scalp for around 3 years. I thought I was having an allergic reaction to my shampoo so switched brands, added tea tree oil to the shampoo, apple cider vinegar ... Then my eyebrows became itchy, then my nose, then forehead and chin and eyelids ... When the itchyness became unbearable (9 months after it started) I went to a derm doctor and was diagnosed with SD...
Now I am Effaclar duo for the face and Cyclopox olamine & zinc shampoo.
Like you, I did not have flakes on the scalp (only pimples). My face is not flaky either, it only itches.
So my advise is: take care of this before it grows and spread to your face. Because then it will be more difficult to treat.