Brief Answer:
These things generally settle in 1 to 3 weeks

Detailed Answer:
Hi.
Thanks for your query and an elucidate history.

First of all I would like to agree with you about the fact that any problem for the first time and something like a swelling in a healthy female of 29 does cause a lots of anxiety and stress. I would say this is really good that you are aware of the possible causes and this attitude alone can lead to earliest possible diagnosis and curative treatment.

I would like to know a few things to make the picture clearer :

1) Have you had any wound in the respective upper limb, may be just a trivial one, or in the same side of the breast or armpit itself may be during clearing the hair or so ?

2) Are you taking any anti-inflammatory medicines like Ibuprofen or so?

3) Any history for flu / fever in recent past?

4) Does the skin move with the swelling as if attached to it (Sebaceous cyst) or moves freely above the swelling (Lymph node)

My views :
Please take an anti-inflammatory medicine like Ibuprofen along with Doxycyclin ( which you are already taking) for 7 to 10 days.

You can take another course of antibiotic and anti-inflammatory medicines for a further 7 to days course.

IF in the meantime or at the end of treatment if there is no regression the best investigations is FNAC-

Fine Needle Aspiration Cytology preferably under ultrasonography guidance. This is one investigations that helps to alleviate the fears and anxiety. Biopsy is done only if FNAC is not conclusive.

Secondly if the swelling vanishes within 1 to 3 weeks of treatment, nothing more need be done and the best part you just have to forget about it ( cancer nodes do not regress at all on antibiotic treatment).

And cancer nodes do not appear all of a sudden too. And they do not cause any symptoms at all in the initial phase and you have these nodes just for a few weeks ( ref: your previous query)

Your main Question:

The Lymph nodes can take 1 to 3 weeks to go away with a proper treatment.
First of all you have to get it confirmed it is lymph node or just a boil by an examination by a Surgeon.
The sebaceous cyst or a boil are adherent (attached ) to the skin and the skin moves with it.
The lymph nodes are deep within and the skin moves freely above it.

I hope this answer helps you to get a perfect line of thinking / diagnosis / treatment .

Please feel free to ask for more if you need to.

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Brief Answer:
Try FNAC if possible, continue medicines .

Detailed Answer:
Hi.
Thanks for your feedback.
Noted your history of no injury you were aware of, a small marble that can move around- indicates to be a lymph node as also the history of a dull ache.

Ibuprofen should be taken at 8 hourly interval preferably after food as the indication here is an anti-inflammatory action to reduce the edema and swelling of the swelling. This will aid in early resolution and also controls the pain.

Possible sinus infection may not cause the lymph node in the armpit.

Any lymph node bellow the size of 1 cm is taken as a reactive lymph node unless proved otherwise., hence your Doctor told you so.

Wait till the medicines help you. FNAC is just to make sure and alleviate the fears.

I hope this helps you, please feel free to ask for more if you need to.

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