Hi, thanks for writing to HCM.
From the given description, I feel that it could be a FURUNCLE
. This is nothing but an infection of the hair follicle by stap.aureus bacteria resulting in a small, firm, red lump under the skin which will be very painful to touch and the surrounding skin will feel warm due to inflammation.
This generally responds to a course of appropriate antibiotic along with antiinflammatory medications.
Intermittent hot fomentation is helpful in reducing the swelling.
Hope this information is helpful. Good day