that's a flegmasia alba dolens also known as milk leg and it means there is a deep venous thrombosis causing the extremity to become ischemic and eventually could develop a necrosis and complete loss of limb
Its phlegmasia cerulra dolens i.e. painfull blue leg in the other leg you thought of p abla dolens but its the normal leg aftected one is left leg
You are right its a sever form of DVT leading to phlegmasia cerulea dolens i.e. painfull blue leg
Definitely DVT likely involving femoral/pop arteries. Initially fragmin and warfarin therapy maybe a filter covering the femoral artery as well.