I suffered from these exact symptoms. after 6mos. of incorrect diagnosis I visited a Vascular surgeon. He saved my legs. Instantly upon examination he said, "I dont have to do the test (ultra sound pen thingy). This is severe lymphatic overload caused by Chronic Veinous Insufficency. *HINT* should you hear this anogram P-A-D run screamin into the night. Your Dr. hasnt got a clue, just a good grasp of the alphabet.
It is genetic in general. It can be caused by life style. What it is, lymphatic fluid is not being properly being returned to the system and is pooling in the lower extremities. Mine actually split the skin and a amber fluid would leak, LOTS of it.
You are going to end up with your legs elevated from several days to several weeks. You'll need a PROTIME/INR and to be on the alert for blood clots. I ended up with DVT/PE, IT HURTS!
STANDING STATIC FOR LONG PERIODS can bring this on. The layman interpertation the little valves in your veins in your legs have collapsed. While managable there is no cure.