Dehydration with Renal Colic: This condition can lead to tachycardia due to hypovolemia, syncope from dehydration and pain, and kidney pain from renal colic. The combination of symptoms can be explained by severe dehydration causing both renal colic and hemodynamic instability.

Pyelonephritis or Sepsis: Infection of the kidney can cause severe pain, lead to systemic inflammation, and result in tachycardia and potentially syncope if severe enough to cause sepsis.
Nephrolithiasis with Obstruction: A kidney stone causing obstruction can lead to severe pain (renal colic), and if it leads to significant dehydration or infection, it could result in tachycardia and syncope.
Cardiac Arrhythmias: Certain arrhythmias can cause tachycardia and syncope. If there's associated kidney pain, it might be due to a systemic condition affecting both the heart and kidneys.

Pulmonary Embolism: Although kidney pain is not a typical presentation, a large pulmonary embolism can cause tachycardia and syncope. If the kidney pain is referred pain from a pulmonary source, this diagnosis could be critical to consider.
Aortic Dissection: This is a life-threatening condition that can cause severe pain (often described as tearing), which might be referred to the kidney area, tachycardia, and syncope due to cardiac tamponade or severe aortic regurgitation.
Cardiac Tamponade: Accumulation of fluid in the pericardial sac can compress the heart, leading to tachycardia and syncope. Kidney pain could be a referred pain or due to a systemic condition.

Pheochromocytoma: A rare tumor of the adrenal gland that can cause episodic hypertension, tachycardia, and potentially syncope. Kidney pain might be associated if the tumor affects renal function or causes an abdominal crisis.
Vasculitis (e.g., ANCA-associated vasculitis): Systemic vasculitis can affect multiple organs, including the kidneys, causing pain, and can lead to tachycardia and syncope through various mechanisms, including cardiac involvement or severe systemic inflammation.