From your description sounds like an abscess
that is formed. Abscess occurs as a result of bacteria infection usually staph. Topical or oral antibiotics
could help with that. You will need to allow it to heal or later on burst on its own (because if you try to scrap or burst it you might find yourself creating a wound that will easily get infected). If not red and painful it will be difficult to differentiate it as a cellulitis
except it can be seen and examined by a health care practitioner. I think it will be safer to visit a clinic so that it can be checked properly (in case it is not a still developing severe condition).
Hope this helps