The pooling of blood in the leg can be due to DVLT or deep venous leg thrombosis. You are using antibiotic to to treat possibility of infection. The DVLT can be diagnosed by venography, D-dimer blood test, doppler ultrasound, plethsmography. If DVLT is diagnosed then doctor might use medicines like heparin. Your pain is directly related to DVLT. Treating this problem will also eliminate pain. For more details, visit DVLT.