This can be the granuloma
formation at the site of infection, which is resolving. This granuloma formation is part of body immune system to restrict the spread of bacterial or fungal infection
from the site of infection to other part of the body. There is sometime fibrosis
also taking place at the site of infection which takes time to resolve and present as bump in the skin. Since the CBC blood test
and q-tip swab is negative, it shows that infection is not present there and this bump will hopefully resolved by time and I think do not need any intervention.
Thanks and take care and wish you good health.