Fluid and Electrolye Imbalance - I am an athlete, I eat a very strict low carb high protein diet. I?

... run 4 miles every day and live a healthy life style. Last month I gained 25 lbs for no reason.NONE of my clothes fit, my entire body is swollen and laying or leaning on things leaves an indent in my skin for prolonged periods of time. What do I do to get rid of this heavy weight