I studied your query in all the details put forth by you.
I understood your health concerns.
Cause of the health problems you queried-
The lump on the arm is -Post-Injection Lump ?
Injection Abscess mostly.
As you have all the history for it.
Remedy-
Cold Compresses would help you more.So stop the hot compresses.This would help still if full blown abscess is not developed yet.
If you have
fever with it,consult your ER doctor and
Take Antibiotics and anti-inflammatory under his cover.
If it still grows worst, I would advise you to consult ER Surgeon, who would treat it by Surgical
Drainage,if need be,after needful investigations.
As I don't have any direct photo of the lump / or not many details from you, I would advise you to consult surgeon.
Hope this would resolve your query with full satisfaction.
Welcome for any further query in this regard to ME by direct question at HCM.
Write excellent review and hit thanks, to narrate your experience ,which would improve my rating for many other visitor's to HCM.
Wishing you fast recovery.
Have a good day.
Dr.Savaskar M.N.
Senior Surgical Consultant.
M.S.Genl-CVTS