Please help us to know our problem.

Hi Doctor, My brother had a hernia surgery on the left side of lower abdomen in the August month of August. After two months, he observed there was a bump on his back side. After a few visits he had a small sivak cut on the bump and removed the pus from there and added a band on it. But every time when dressing on alternate days so much pus is coming. He went to hospital and was diagnosed with many tests but the doctors are unable to identify why exactly the pus is coming again. He is suspecting that either bone tb or done tb or some other but in the tests no where any body had mentioned anything positive. All results are coming as negative. Today he got one scanning of the spine lx, Attached the reports and scannings. Can anyone please tell us the problem. We went to both private and govt hospitals but no one confirmed what the problem was. Feeling well at help less. Please help us. In scanning, on the right side there is a small cut, from there the pus is coming.