From the description, it seems like a furuncle or a boil. You may try doing warm water compresses followed by application of fusidic acid
cream. If painful, you may take over the counter analgesic
to relieve pain. However if the lesion does not heal, consult a doctor as a course of oral antibiotics
might be required and in severe cases drainage of the lesion might also be required.
Hope that answers your query. Take care.