A 23 year old male who has normal complains of mild pain in his right iliac fossa in a waveform pattern, which increases during the night and he becomes exhausted, is admitted in the hospital. On examination there is mild hematuria. Urine examination reveals plenty of RBCs, 50WBCs/hpf and Urine pH 5.5. Which of the following is the most likely diagnosis?

The presentation of waveform (colicky) pain in the right iliac fossa that worsens at night, along with microscopic hematuria (plenty of RBCs) and WBCs in acidic urine (pH 5.5), is classic for ureteral calculus. The waveform pattern indicates ureteral peristalsis against the stone. The hematuria and WBCs indicate mucosal irritation and possible infection. Glomerulonephritis typically doesn't cause colicky pain, and bladder cancer usually presents with painless hematuria without the characteristic colic pattern.