Okay, I've had enough.
My right knee has bugged me with sharp stabbing pains on random occasions; sometimes when I go up and down stairs and when I jog. The pain is concentrated just below the knee cap (I think). I need to stop whatever I'm doing (running or walking) and use my umbrella as a walking cane whenever the knee pain attacks happen. When the pain first came up (when I was still in high school), the doctor said if the pain recurred, my knee might need surgery. I was naturally scared; hence, I haven't gone back to the doctor with that complaint. Many years later: recurring pain, especially when the weather goes cold.
The right foot, on the other hand, started becoming painful after I fell down a flight of stairs in 1997. Since then, whenever I walk or run more than 1 km or play an extra long game of badminton, there's pain on the mid-foot, on the same side as the big toe. This pain gets worse with the cold weather, so I wear socks to bed and I walk with a slight limp at night. My right foot has become more painful since November 2010; I suspect that extended walking and use of leather pumps worsened the injury in my foot.
It looks like I have to go back to the orthopedic doctor and have my knee and my foot checked. Last time I was there, my right wrist was suffering from de Quervain's tenosynovitis (the wrist was abused by the excessive typing I was doing; back then, I was rushing to finish my thesis manuscript).