Sewage odour in borewell water

I am experiencing the smell of sewage in my 5 years old borewell after the heavy rainfall in January. Till January 2021, the water was very clear and tasty. Two times we have flushed the bore using compressor, but within three days it smells again. We put a bore 6ft away from the old bore and on the first day the water was clear and with no odour, but on third day sewage odour comes. We have tested the water and attached the lab report. Please recommend what to do next.