Hello,
Thanks for your inquiry,
You are c/o of Painful bump in the right side rear of head, which hurts on turning your head to the left side, not visible only able to feel, and a feeling that it is getting bigger - all within one hour. A single allergic bump is rare without
severe itching. I think there should have been a pre-existing mild bump which has been infected and because of the pain you have noticed it one hour back.
A hair follicle got infected may present like this - summer boil.
If it is a
lymph node got infected - watch for any source of infection in the
scalp or neck anywhere around that region.
If the bump is covered by intact skin and if you are able to lift the skin in the bump area - then chances for a lymph node or a mini
Lipoma got infected.
If you are able to see a small dark spot in the center and you are not able to lift the skin it may be an infected sebaceous cyst.
Antibiotics + pain reliever + avoiding
injury by a comb will relieve the symptoms.
If it persists and gives problem consult a Dr.
Best wishes