Pyelonephritis or Upper Urinary Tract Infection: Given the presence of fever, body aches, headache, and the urinalysis (UA) results showing some glucose and small blood, an upper urinary tract infection is a plausible diagnosis. The lower back pain could be indicative of costovertebral angle tenderness, a common finding in pyelonephritis.

Musculoskeletal Strain or Degenerative Disc Disease: The patient's age and the presentation of lower back pain could suggest a musculoskeletal issue, especially if the fever and systemic symptoms are mild or transient.
Prostatitis: Although the UA is not significantly abnormal, prostatitis could present with lower back pain, fever, and body aches in a male patient, especially if there's an element of urinary frequency, urgency, or discomfort not explicitly mentioned.
Early Sepsis from a Non-urinary Source: The combination of fever, body aches, and headache could indicate an early stage of sepsis from a source other than the urinary tract, which would need prompt identification and treatment.

Spinal Epidural Abscess: A serious condition that requires immediate attention, spinal epidural abscess can present with back pain, fever, and systemic symptoms. It's crucial to consider this diagnosis due to its potential for severe neurological consequences if missed.
Spinal Osteomyelitis or Discitis: Infections of the spine can present similarly and are critical to diagnose early to prevent long-term damage or neurological deficits.
Abdominal Aortic Aneurysm: Although less likely given the absence of specific symptoms like abdominal pain, an expanding or ruptured abdominal aortic aneurysm can cause back pain and should be considered, especially in an older male patient.

Inflammatory Arthritis (e.g., Ankylosing Spondylitis): While less likely given the acute presentation, certain types of inflammatory arthritis could present with back pain and systemic symptoms.
Cancer (e.g., Multiple Myeloma, Metastatic Disease): In an older adult, cancer should always be considered in the differential diagnosis for back pain, especially if there are systemic symptoms like fever and weight loss.
Endocarditis: Although typically associated with more specific cardiac symptoms, endocarditis can present with non-specific systemic symptoms like fever and body aches, and it's a diagnosis that should not be missed due to its serious nature.