My Dr Has Just Prescribed Celecoxib 200mg In Place Of

My Dr has just prescribed Celecoxib 200mg in place of Libraz, which is no longer available. In doing a little research, It seems the Celecoxib treats entirely different symptoms, than Librax. I deal with IBS & other intestional conditions. It seems Celecoxib would worsen these conditions. It also states do not take if allergic to sulpha, which I am. Should I question my Dr. choice for an alternative medicine for librax