Eliviu,
I had erythema nodosum on my lower legs for 18 (!) years. Had 4 biopsies on them. At first they linked them to the Hodgkin's Lymphoma I had, but even when I was cleared of the cancer, they kept on being there, for 18 years in total.
I had numerous tests, but they would only look at the erythema nodosum itself, the doctors wouldn't even listen at all the other symptoms I had. Got chest X-rays, nothing came out of it, also a full rheumatoid arthritis checkout. Until 2,5 years ago - this Dr saw them as an indicator of something going wrong in my body (a person doesn't have an inflammation for 18 years with no reason was what I was thinking), he kept on searching for a cause, I had 2 negative zoonosis tests (Bartonella/Borrelia/and some others). After being on GCmaf for a year or so, suddenly another Bartonella test came back positive.
Erythema Nodosum has been found on patients with Bartonella.