Which specialist must i see for a pain in the groin area mostly with movement?

Groin means different things to different people. People call the various parts the groin. Testicle, scrotum, vaginal area, hip, thigh, inguinal region. So we need more details. Often groin pain in a 72 yo is from the hip.

I agree with Dr. Romano that more description of your symptoms is needed in order to advise you but I would point out that unless you recently strained your groin ligament, that groin pain is very often a sign of osteoarthritis of the hip joint. In this case you would consult an orthopedic specialist if you think this applies to you.