I think a lot depends on your friend's age. Older people tend to get swollen puffy ankles caused by a heart weakness. Sometimes a cough occurs too, if fluid is also retained in the lungs
At younger ages, certain conditions cause there to be more watery fluid retained inside the body. Innocent causes are female hormonal, and more serious causes are kidney problems. Neither of these is classically associated with a cough.
All body water is supposed to circulate. The fluid part of the blood can separate, temporarily, but it is supposed to return to the heart via either the veins or via the lymph system. So a third cause is, that anything that blocks the return of the normal fluid, will cause it to collect.
In the vein line, blockages or blood clots in the veins can cause drainage problems from the legs. At worst, a cough might represent a blood-clot in the lungs, or a lung cancer causing a blockage in the main return-vein from the legs,
The calf and leg muscles in action, are supposed to help blood return upwards in the veins, via a valve system. If there is no muscle action, - I.e. prolonged standing, - some puffiness may occur in the feet.
In the lymph system line, some tropical illnesses cause the lymph drainage channels from the legs to be obstructed.
A fourth cause is thyroid hormone problems, - usually too little thyroid hormone, causes a special type of non-soggy swelling in the lower legs.
I don't think you can be expected to diagnose or manage your friend's condition; - it needs detailed thought by a doctor, really.