Final answer:
The condition that should be suspected until proven otherwise is Acute femoral artery occlusion.
Step-by-step explanation:
The condition that should be suspected until proven otherwise in this case is Acute femoral artery occlusion.
Peripheral artery disease (PAD) is the narrowing of the arteries other than those that supply the heart or brain due to atherosclerosis. It most commonly affects the legs and can cause symptoms like leg pain, skin ulcers, bluish skin, cold skin, or poor nail and hair growth. In this case, the patient's right lower leg being cool and pale with rapid-onset pain suggests a potential occlusion of the femoral artery.
It's important for the patient to seek immediate medical attention for proper diagnosis and treatment.