Chemo Drug Rituxin & Hep B

Does Anybody have any information about the Link of recieving The Chemo Drug Rituxin ( For A Non Staged Liver cancer) for almost two Year ( since June 2016) and Now Testing Positve for the Hepatitis B Virus ( May 5th 2018) HBSAG Positive, was negative 11/16/2014, HBC T Positve was Negative 11/16/2014, AHBS 4/15/15 <3.1, 3/15/18  6.0. Any and all information is Very Much Appreciated I am freaking Out!