Thanks for the additional information.
Most likely the lump you are describing is a fiberous mass, which are fairly common and nothing to be concerned about.
If, however, the lump begins to enlarge, becomes tender to the touch or feels warm to the touch, or does not go away within a few weeks you should be seen by your doctor.
You should also mention that you had a lump to your doctor during your next visit, in order for him/her to further evaluate things - it is possible, although unlikely, that the mass is a sign of something more serious.
Sincerley,
Emily
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