I have a painful and itchy sebaceous cyst on my chest, it has been there for the past 6 months or so and has never given me any problems, however over the past weekend i started hot compress and its now itchy and painful with no centre head either?

Cyst: Use of heat could^ blood flow which may cause itching or your may have burned your skin if compresses were too hot. If this is a sebaceous cyst- they often resolve on their own or they may remain without causing problems. If there is a lot of redness, swelling, heat, tenderness - this could have become infected. Occasionally a cyst may need to be excised. Talk to your doctor if this worsens.