My Son Age 31 Is Visiting Relatives In Southern China

My son age 31 is visiting relatives in southern China . He is concerned about his ankles swelling- left is worse than right- some mottled redness he said. They have been there for 3 weeks- did a lot of hiking two weeks ago and had the same swelling but it went away. Last weekend he rode a bus for 2 hours and it came back. He takes BP medication - no headaches or dizziness. Six weeks ago he had same day surgery to correct a deviated septum but recovered. He has lived in China before- 4 years ago and never had this problem. Is it related to his surgery? I think he should go to a dr in china