welcome to health care magic
Regarding your query,the lipoma
you have is silent for the past 15 yrs..
but now it is causing problems..
Lipoma getting infected is a rare entity..
however when it gets infected you need to control the infection first by taking antibiotics and pain killers to relive pain..then remove that lipoma by an surgeon..
Because of that infected lipoma you got fever chills
Hope you understand my suggestion.
consult surgeon for more suggestions