hi, my father is 63 and he is diabetic. around 15 days back he noticed a lump at the neck near the collorbone,he ha s fever too which generally rises in the evening, blood test was done ,the lump was described as supparative lesion ,all other tests are normal except his esr is 86,chest x-ray is also normal.he is on antibiotics for last 15 days ,lump is now smaller in size but he is having high fever which is going up to 102,what can be the reason, please help