I have a small hard bump in the middle of my head it feels like is part of my skull but i never felt that before and it doesnt hurt what could it be?

Cyst: Most common non painful bumps that spontaneously appear are due to sebaceous cysts / oil glands gone wild or lipomas, fatty tumors. These usually are cosmetic and should not require surgery. Get checked if there is any doubt

Skin condition: Very hard to say and you did not mention where it is located. If at the back of the head - base of the head at the neck - it may be a lymph node. If it gets larger or more painful, see a physician.