I have a vein in lower right thigh just above my knee that is visible for about 6" and is tender. no redness or swelling that i can tell.

See vein specialist.: What you describe sounds like superficial thrombophlebitis. You should see a vein specialist for a venous evaluation. In the meantime, try wet compresses to the area and ibuprofen.

Varicose vein: This is due to a reflux point and pooling at the area in question Evaluation by a venous Doppler sonogram would be the first test,which would identify the problem and help with establishing a treatment plan