If you feel like putting a non-lethal curse on somebody, curse them with a case of Plantar Fasciitis. It's like an epidemic these days.
It's a common affliction of the middle-aged (like Frozen Shoulder), and usually there is never an identifiable cause although weight gain seems to be one. It can be in one foot or both. Sometimes it can be easily fixed with ice and stretching but it can be a chronic problem which eventually will disappear as mysteriously and suddenly as it appeared.
The most common symptom is feeling like somebody put thumbtacks in the heel of your shoe. The problem is not your shoe (although arch supports sometimes help it). The problem is inflamed tendons.
The differential diagnosis is Achilles Tendonitis.
Besides the pain of simple walking around, Plantar pain can lead to other joint or lower back problems because of altering one's gait to minimize the foot pain.
Some basics on Plantar Fasciitis
More info from the Pain Doctor