Hello,
Thanks for the query,
You are probably suffering from
pustular acne.
It is a moderate variety of acne and often involves the back and neck.
The other possibility is recurrent
folliculitis.
You may require treatment with
oral antibiotics,
as pus means infection.
Please meet a
dermatologist for exact treatment.
Let me know if you have any other doubt.
you can ask a direct question to me on this forum, following the below link.
http://www.healthcaremagic.com/doctors/dr-rahul-kumar/64818
Wishing you a good health.
Thank you