My 22 Year Old Daughter Is Having Swelling In Her

My 22 year old daughter is having swelling in her calves, ankles and feet.. as far as I can tell, no pain, just swelling discomfort. She is on her honeymoon and has been on her feet alot, plus, drinking lots of pop (in another country), recently on birth control, etc..... I'm concerned about her.. As her mother, I too, have a tendency to retain fluid (evident in my right leg), especially after drinking pop..