What Causes Lower Leg Pain?

Yes, I am looking for some answers to my father-in-laws condition. He is Spanish, so I want to understand so I can help him better. He used to work in fields when there was a lot of water, sometimes cold. Now he has pain in his lower legs and takes shots to help with the pain. I would like to maybe find him a doctor here for a 2nd opinion. Can you give me any insight, please. Thank you