im 28 and week ago i found a swollen place on right leg that goes from behind the knee and around that vein on the pic and i just sense sometimes burning and little pain on that place so my question is this a lymph node that is swollen or i could really have problems with veins already
Definitely it's not lymph node. There were no lymph nodes present at that place. Behind the knee joint.  Normally in the legs with swelling that subsidies immediately after elevating the leg from the ground in supine suggests venous engorgment.  Your symptoms suggesting that it may be synovial cyst.  Maybe bakers cyst.  Consult orthopaedic surgeon. May requires surgical excision