When traveling, many knees hurt. What should I do?

It may be meniscus injury or fat pad muscle injury.

Reduce exercise and knee joint weight-bearing activities, especially when going up and down stairs. You can apply local hot compress, buy some plaster or topical medicine to promote blood circulation, remove blood stasis and relieve pain. If the pain is obvious, you can buy knee pads for protection. If the improvement is not obvious, I suggest you go to the hospital for an MRI vibration and a preliminary diagnosis.