I scratched my head a lot.
It was neither the kind of head scratching that makes you look smart, nor was I relieving a pesky itch. I had a combination of digging and scratching; I would absentmindedly run my fingers through my hair, digging them into my scalp.
With my nails I scraped dead skin and oil from my scalp, then depositing the resulting waxy substance on a tissue and throwing it away. Sometimes I scraped so much that my fingertips would be tinged with blood. In such cases, I would wipe off the blood and return to my head scratching, just in a different location.
Eventually, the blood would form little scabs which were invisible to anybody who might look at my hair-but I would feel them during subsequent head scratches, and then I lodged them from my scalp. This resulted in a perpetual cycle of blood and scabs that remained with me throughout those months.