Hi. I Have Developed An Infection Under My Scar 7

Hi. I have developed an infection under my scar 7 weeks post rotator cuff surgery. GP put me on flucloxacillan yesterday and I am just wondering how long it normally takes to help alleviate symptons. I went from being pain-free to having pain during sleep and normally daily activities like walking. Progress had been great before that. My scar was always nice and clean but the skin around the edges was quite lumpy at first... it had smoothed out rather nicely but now is a bit lumpy again, there is redness and it is warm. STarted the antibiotics yesterday. Flucloxacillan 500 mg 3 x per day