Hi there. There are numerous causes of dizziness arising from all the organ systems like high and low blood pressure, heart attack, arrhythmias and cardiomyopathy, brain diseases like stroke, tumor, headache, migraines and hyperventilation, confused mental state due to medications, drugs or alcohol, medications like blood pressure meds, sedatives, some antibiotics and most important, dehydration, blood electrolyte changes, hypoxia, hypoglycemia etc. Neuropathy due to diabetes, orthostatic hypotension due to aging, anemia and infection can all cause this symptom. You will need a detailed evaluation including electrolytes, and renal function tests since you had post renal failure due to obstruction. Hope this will help. Take care.