Swelling On Feet Radiating Upwards, Subsides Within Days, Have Weight Gain, Discomfort, Breathing Difficulty With Dizzy Spells. Cause?

my feet have been swelling up pretty bad. The left one usually gets bigger than the right. Last week it was so bad I could actually watch the swelling, it started moving up my legs. I felt like they were going to explode. I also gained each time from 12-15 pounds in 1-2 days time. It goes away within a few days, it also takes about a week for the weight to go back down. It is very uncomfortable. I didn t notice until recently that I have a hard time breathing . I am also having dizzy spells.