Calf pain, feet sweelling, shortness of breath...

[Mandy519]

My husband has feet swelling (ankle and top of feet), on and off.  Sometimes he wakes up in the middle of the night saying he has calf pain, when I massage his calfs it seems to help.  He had a knee replacement in 2006, and he's been in pain on and off since. But, what worries me the most, is everytime he walks just a little distance, he is out of breath, he says it is because he is in pain.  He is 44 years old, and weighs 355 lbs, he's a smoker.  I tell him to see the doctor but he says he is ok, nothing to worry about.  One night at work last year, he had heart palpitations, sweating and shaking, he was sent home, he was tired for about two days, but never had these symptoms since.  Could someone tell me what these symptoms could be about.  Thank you.