About three years ago I noticed that the skin on the upper back of my legs from right under my butt to the middle of my thigh is rough. Not long after that I noticed pimple like bumps in the same area. They can last anywhere from thirty minutes to a few days and they hurt. They're most irritated when I wear shorts or sit on them. A friend saw them and she said they looked like bug bites. I've tried popping one to see if it was a pimple to no avail. For the roughness I've tried paying special attention to shaving that area to make sure it wasn't hair, washing the back of my legs with several different exfoliants to see if it was dead skin and washing them extra. Nothing's worked and I'd really like to find out what it is so I can get rid of it. 

I'm fourteen years old and I'm very active.