A 38 year old male presented with fever for three months,no h/o weight loss, Blood culture, urine culture negative, CXR normal, OCC joint pain.Haemoglobin on the lower side, PET scan s/o multiple subcarinal nodes not amneble for biopsy.Serum Ferritin marginaly raised, ESR and CRP significantly raised.ANA negative RA factor Neg. What should be done in this case?