Recurring Swelling In Feet Post Triple Bypass. What Can Be Done?

My husband had a triple heart bypass about a month ago. His legs swelled up enormously to just below the knee . He was hospitalised and given treatment, and the swelling subsided. I have been told this is water retention. However, he also had fluid on his lungs which was causing extreme pain. He has been discharged from hospital, bt his feet (both feet) are now starting to swell again and it look as if, if left unattended, he could end up with swollen legs again. What can I do to help him, or should I take him back to the hospital? We live about an hour and a half away from the hospital where he had surgery.