I have a cyst on the back of my head underneath scalp, a week ago it was hard grape like now it's like it went down. worried ?

Cyst: Cyst was hard and now it has settled , with this history possibilities are that it could be lymph node, boil, sebaceous cyst which had got inflamed . Only way to confirm is the examine , so please consult a doctor.

No: Generally bad things don't go down. They stay big. So most likely just a pilar cyst. If painful or growing see a surgeon to remove