My Surgon Just Lanced A Cyst Or Thrombosis Hemorrhoid Near

My surgon just lanced a cyst or thrombosis hemorrhoid near my rectum today. I am already on cephalexin and he also proscribed flagyl but I am concerned as I have never taken this drug. I have had Hotchkins lymphoma 4 years ago and see this drug is hard on the liver. My Billy Rueben is always high around 1.9 I am nervous about taking this drug.