Flat feet problem. Doctor in nagpur?

Hello Sir/Mam, I have flat feet, which is severe on right feet (3rd degree) and on left it is 2nd degree, according to the internet. My feet, while walking, which are supposedly to be straight, are inclined to 30-35 degrees. I start to have noticably severe pains if I stand more than 10 minutes. While, walking, which I do for exercise, I have to stop well before my actual capacity, due to the pain. This condition was brought by our family physician while a regular check-up. After he examined, he told that the flat foot was flexible, and not severe. He suggested me to see an orthopedic doctor. Before that, I tried braces shoe insole, but rather than easing the pain they increased the pain. I also feel the flat feet are affecting my posture. I'm an engineering student, aged 20M. I want to take part in some sporting events, but due to this I can't. I live in Nagpur. What are the steps I need to follow? And, can you please tell if this is curable and suggest a good doctor in Nagpur? Thanks