Legs turning blue and painful

(25F) When standing up for more than 15 minutes my legs turn blue and painful. I can walk for around an hour before it gets painful and they are exhausted the rest of the day. Theyve also started falling asleep very quickly when both sitting and laying down. I have no idea if it’s muscular, neurological or vascular and my doctor shows very little enthusiasm when i bring it up but it’s starting to affect my life quite badly. I am 165cm, 67kg (recently gone up 7kg for no particular reason), physically active and no other diseases. I’ve had rhabdomyolysis twice in 6 months also for seemingly no reason.

Any tips?