Suggest Treatment For Infection After A Partial Knee Replacement

I had a partial knee replacement 4 weeks ago. Three day s ago I noticed at the bottom of the cut ,which had healed, an infection beginning. Yesterday. I went to the Doctor and he gave me the antibiotic Celeclor , 2 tabs x 3 times daily. Today the infection is much the same , no worse but not better. I wondered if I should be taking Flucloxacillan instead of the Celeclor as the infection is after a knee replacement?