Boy. 7, with intermittent upper right thigh pain for a couple weeks. Says it makes a popping sound at times. Causes? How soon should he see his ped?

Thigh pain. Make an appointment to see your pediatrician as soon as possible especially if he is limping.
"popping" Makes hip as origin more likely. Should see pediatrician soon, but not er, as may need imaging versus pt or observation.