I had some minor symptoms at about 15 while playing soccer and when standing for long period. Pain became constant while standing at age 33, now 13 years ago. Pain in back of legs and buttocks started maybe 5 years after that. It sucks.

Eat a healthy diet, lots of veggies and fruits, exercise, stretch, meditate or something to help with stress. There are all sorts of meditations on youtube. Smoothies are a great way to get in health foods. A blender breaks many more of the cell walls than just chewing does, anyway chewing gets tiresome. For example you can drink a whole carton of blueberries in a few minutes. There are lots of frozen fruits in packages at the store. I know you didn't ask, but I feel obligated to say these things because I think this would help most people a great deal. Look up Drs T. Colin Campbell, McDougall, Ornish, Fuhrman, Barnard.
Ron