Pain behind knee cap. bulging foot veins. leg hurts when pressure applied. cramping in calf and thigh. neg ddimer and ultrasound. what could it be?

Chondromalac/compart: When knees develop early tendonitis change, there can be periods of flare where inflammation and pain can develop behind the kneecap due to cartilage tears. This is also called patellar chondromalacia.There is also concern for compartment syndrome given your vascular complaints. It is thus best to see a Sports Medicine &/or Vascular MD to diagnose what is going on and make sure of the diagnosis.