Fever, LUQ tenderness, pleuritic left upper pain referred to the scapula and reduced left basal air entry after splenectomy suggest a subphrenic abscess (pus under the diaphragm), which most often follows surgery such as splenectomy. Basal atelectasis is also a pulmonary complication, but it would not explain the high fever with LUQ abdominal tenderness at day 7.