Thanks for seeking advice through HCM.
You seem to be having an abscess
which needs a lot of hot water fomentation. For GOD's sake don't puncture it with a needle as it can complicate things. As it is a month old the pus / secretions inside could be very thick & hence may need surgical excision called I&D[Incision & Drainage] by a surgeon.
You may also need antibiotics & anti inflammatory drugs.