I have noted the contents of the mail with some interest as I do not find there to be any scientific explanation for these symptoms. It is not unusual to have unilateral swelling involving one limb, which may be of sinister significance. It may be an indication of the deep venous thrombosis. This condition though common in the lower limbs does occur in the upper limbs as well. Swelling of the both lower limbs is usually associated with heart disease, kidney disease and also seen in the elderly people due to inactivity or low protein state or both. I note that the questioner has been investigated for these and found to be not suffering from these illnesses. This leaves one without any plausible explanation for intermittent swelling of the one half of body. Occasionally the Mal-development of the venous system predisposes on to develop the swelling but this is usually more permanent. My advice to the person would be to have thorough cardiac assessment, Blood Biochemical profile, and Doppler of the upper and lower limb veins. If all these are normal and the examination by a competent physician is normal then leave things as they are. In case there is frequent problems then there is need to do endocrine assessment. I am afraid there is no easy answer. These symptoms may be totally benign, in which case one need not worry where as sometime these symptom may be an indication of the deeper pathology, which one needs to get the diagnosis of.