The pedicab puts a lot of strain on the joint; is it possible that the thing was not adjusted properly? Here's the old standard formula.... If you have pain in the front of the knee, around the kneecap, then your saddle is too low/too far forward. This means you are "hyperflexing" the knee. Likewise, if the pain is in the back of the knee, you are "hyperextending" the knee as a result of your saddle being too far back or too high.
At your age, it's unlikely you've done any severe damage; I'd suggest a trip to the doc (a sports medicine guy if possible), a brief layoff and standard treatment with the old RICE (Rest, Ice, Compression, Elevation) routine for a couple of weeks.