Hi,
Welcome to XXXXXXX
It is very difficult to precisely confirm a diagnosis without examination and the answer is based on the medical information provided.
It will be great if you mention whether it is associated with pain / not and also the size and duration of it, also is slow growing or not.
Based on the information you have provided i think it is likely to be a sebaceous cyst. These occur due to collections of sebum that accumulate under the skin. It is a are slow growing tumour. It is not cancerous and never turns cancerous. It is a harmless, benign growth. If it is bothering you, you can get it removed. The surgery is a minor procedure and leaves hardly any scar later on.
Hope I have provided the information you needed.
Wish you good health. Take care.

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Hello
Good to hear from you.

If it has turned up in a day i think i might be folliculitis which is inflammation of one or more hair follicles.

Hot, moist compresses may promote drainage of the affected follicles. Treatment may include antibiotics applied to the skin (mupirocin) or taken by mouth (dicloxacillin), medications to control the infection. It responds well to this line treatment, you should be fine 3 to 4 days.

Hope i have cleared your queries. If you do not have any clarifications, you can close the discussion and rate the answer.
Wish you good health.

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Hello
Good to hear from you.
The mastoid lymph nodes (retroauricular lymph nodes, posterior auricular glands), usually two in number, are situated on the mastoid insertion of the Sternocleidomastoideus that is behind the ear, but it is less likely that the cold/cough will cause sudden enlargement.
In any case i advice you to do salt water gargling 3 to 4 times day and also steam inhalation which will improve your symptoms. You can consider taking over the counter medication for cold if required.
Hope i have cleared your queries. If you do not have any clarifications, you can close the discussion and rate the answer.
Wish you good health.

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