I have ankle pain on my right foot since last week. no conditions, no sprains or anything like this... pain when rotating and pressure applied. ?

Depends: Many things can do this at your age: growing pains, stress fractures, infections, inflammation, arthritis. Try over the counter meds and avoid using it or moving it excessively for a while. If it worsens, have it looked at.

Unexplained pain: When you have pain somewhere with no obvious explanation - fell, injury, accident - it could be a sign of disease somewhere. Your ankle should be evaluated by a doctor to see if anything significant or worrisome is going on.

Ankle pain: Anytime one has persistence of pain beyond several weeks ,you should be examined. There are many other causes of ankle joint pain besides trauma.

Ankle pain: If there is no history of a sudden twist or turning of the ankle, you can try to apply an inexpensive ankle wrap to it; however, if the pain lasts for more than two days, go see a Podiatrist who is trained to tray ankle sprains and injuries. You may have had a brief twist that caused this. It should be examined and X-rays taken.