sudden skin eruption

Two days ago, A very, sore lump appeared on my back. It looks similar to a pimple, but it hurts a lot. Around the lump, it is a red. I do not know what it is or what I can do about it. The lump is also smooth, without any entry. It is just smooth and it hurts

[Bhupinder Kaur, MD]

Hello,
This kind of bump can be a swollen lymph node,a sebaceous cyst or a boil. Lymphadenopathy (swollen lymph nodes) is usually caused by a viral or bacterial infection along with other numerous causes.Treatment is usually cold compresses,over the counter anti-inflammatory analgesics(pain killers) like acetaminophen or ibuprofen,antibiotics if cause of infection is suspected to be a bacteria and surgical drainage if there is any abscess formation.

Sebaceous cyst is a closed sac or cyst below the surface of the skin that has a lining that resembles the uppermost part (infundibulum) of a hair follicle and fills with a fatty white, semi-solid material called sebum produced by sebaceous glands of the epidermis.It is usually painless but can become painful if infected.Then antibiotics are needed.

Boils are caused by infection of the hair follicle be staph aureus.Treatment includes antibiotics.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.