What Is The Swelling And Hardness In Leg After A Hip Replacement?

Hi My dad whos 84 had hip replacement 2 weeks ago, Was home and doing Ok then leg swelled up and was rock hard, been back in hospital since last weekend and still not much change. he is on warfren and given ice packs, the Dr says it may be clot??? How long will leg take to go down. Sore when walking with frame