Ramla, 65 yrs old male, presents with low back pain especially at L3, anaemia and fatigability. His investigation profile reveals - Hb = 7 gm%, TLC9000/cmm, DLC -N- 55%, L-30%, M-10%, E-1%, B2%, Serum proteins-8 gm %, ratio-2.9/5.9, ESR-90 and serum creatinine-3.2 mg%. Likely diagnosis is :