Painful scalp bumps
Dissecting cellulities of the scalp is a rare autoimmune condition which causes painful, swollen, and draining bumps on the scalp.
It is similar to hydradenitis suppurativa, which occurs in the groin and under arms. Both are genetic, and hard to treat. They are painful and can leave scar. You cannot treat these yourself at home, you must find a good dermatologist to help you.