Mechanical irritant dermatitis
What is inside the itching? #dermatology
The outer skin of the little lump is decapitated with a needle, revealing a small thorn. Then the rest of the spines are "combed" with the needle, scratching the skin.
At some point, it will start to bleed. Use a nail clipper or similar to remove as many raised spines (or bits of them) as you can.