Expired beer from Pick N pay Family in Secunda

Pick N pay family liquor I bought few drinks on their liquor store,including Sminorf Pinetwist that is my favorite drink,due to it being on special I bought plenty,during the weekend of kf the 30th I drank it,3 or two,I ddnt sleep night diarrhea the whole night.i have always drank it Pinetwist before but it have never given any problem,the following morning I have to check the expiry date it has expired 052021,on the label it says bb052021.when I get to Pick n Pay liquor family the Manager,supervisor a white guytold me that BB means manufacturing date,I'm not stupid I know best before means use before this date,The attitude I got from that guy was out of this world,he just look down on me like I'm crazy.