Thank you for the information,
There can be a few possibilities.
It can be an inflammation or infection.
Infection of hair follicle or folliculitis
can occur there.
An inflamed cyst is also possible.
You can apply warm moist compress over it.
Neosporin antibacterial cream can be applied.
If it does not subside or increases in size, please take an examination by doctor.
If the pain is much you can take paracetamol.
I hope this information helps.
I will be happy to assist, if you need any clarification.
Please feel free for any follow up query.