Noted your short history of getting over with a bad Shingles
and found out that there is a definite lump on the chest wall that is hard.
If you are feeling a hard lump then it is present and hence you should get the following done:Consult a General Surgeon
for clinical evaluation, examination.
Get an ultrasonography
done and FNAC if indicated.
All this will find the cause and get operated to get the lump removed if indicated for 2 reasons:
First of all you get rid of something that is not a normal part of body.
You get a definite diagnosis by histopathology.
Continue management of Shingles as pain may still be present, I know it sometimes takes a long time for to pain to get abolished.
Hope I have answered your query. Let me know if I can assist you further.
Dr. T. Chandrakant, General Surgeon