Hello and welcome to HCM,
Thank you for your query.
There could be a possibility of a muscular abscess
. This would lead to an inflammation and the accumulation of pus in the cavity formed beneath.
You could visit a doctor and get yourself examined. There is nothing to worry about, as it is common for such abscesses in the region of the chest, as the chest has many hair follicles, that could lead to folliculitis
(infection of the hair follicle).
If you are not on any medications to treat this, this could lead to an infection. You might need a short course of antibiotics and a sterile dressing (which the doctor will decide). Which is why I advise you to kindly visit your doctor.
I hope I have succeeded in answering your questions, you could write back to us anytime for further clarifications.