After 3m att & persistent fever, turns out fever caused by rifamycin.what other effective treatment can i use to continue att successfully?

Tuberculosis?: Am assuming you mean anti-tuberculous therapy. Without knowing what type of TB is being treated, whether sensitivities of the isolated M. tuberculosis have been done, and so on, it is not possible to make specific recommendations. There are alternatives to rifampin or its cogeners and these should be determined by your treating doctor. Good luck.