It starts out itching like crazy, then pimples form, and then it gets really sore, and then pustules form and all the hair falls out around the pustules. These pustules will eventually pop and ooze out like a goo with the viscosity of snot. The hair will grow back.
When I was a teen I had acne on the scalp a bit, but after joining the service the condition worsened. The Military barber wouldn't even cut my hair because it covered such large area of my scalp. Military doctors tried everything from doxycycline, minocycline, tetracycline, penicillin, and even the gonorrhea shot ( I'm not sure what that was)... all of which if they did work, only worked while I took them, and it only took days after I stopped using them that it would come back.
I expirimented with the condition in some ways as to pinpoint the cause, but am still stumped... some things I tried were:
-No hot water on my scalp (maybe the pores would open, and let in the bacteria, then when the scalp cooled they closed, trapping the bacteria in)
-I would wash my head twice a day with a brush and cold water.
-I would wash my head twice a day with a brush and hot water.
I also tried not touching my scalp ever, something that worked well with my facial acne.
I also noticed that there is a spot in which the acne always starts to come in first... it's right in the middle of my cowlick, then spreads downward.