I have a hx of varicous veins. Recent trip to las Vegas and back . Wore travel socks both ways and sometimes while in vegas. Started having severe pain in knee when going from sitting to standing position. then it would improve with walking. Now home and continue to have cramping and painful ache in RLE behind knee and thigh.
Your recent travel suggests long hours of legs in a dependent weight-bearing (standing) which aggravates varicose veins. Start wearing above knee compressive stockings plus reduce long hours of standing and walking for a week.  Elevate your legs with the help of a stool when sitting for durations more than one hour. Additionally., learn exercises from a physical therapist.  Hope that helps.  All the best