Suggest Treatment For Left Shoulder Pain

Hello, My mother has been suffering from 2 months with the pain in left shoulder having PUS. She has been diagnosed with TB in the shoulder. My concern is that she has undergone a I & D operation to drain all the PUS(200ml) on 31-Jan-14 but i see that every 3-4 days PUS gets formed again. She is on TB medicine course along with oflox 200mg. So could you please advise when the PUS formation will stop and if any otehr medicine or any other test needs to be conducted