What Is The Cause Of Swelling Of Legs?

hello dr. myself angel khosa frm punjab i want to consult with u about my leg problem.am having swealing on my leg frm the age of 3 yrs.i took a lot of medicines etc,show to many doctors but now specific result came out.i also carried out the test of falaria but it also came in negative aspect ,doctor advised for operation .but they are not able to find out where is the problem ,they are not able to come on a specific point.