 [ Symptoms ] what is an angiogram used to detect heart disease [ Disease ] the diarrhea cold chills and throwing up is more likely caused from the drinking for 2 days with all the throwing up you likely became dehydrated and possibly a bit hypoglycemic your body no longer had the nutrients it needed to function properly drinking excessively and then the likely related side effects of diarrhea and throwing up could have thrown your all ready irregular period off pregnancy only happens if you had unprotected sex with a man if he had an std it could have been given to you depending on the std even if a condom was used the only way to know for sure is to get check for both by your doctor you can take a pregnancy test at home just pick one up at the pharmacy and follow the instructions in the box good luck in the future if you have diarrhea and your throwing up make sure your still drinking water to prevent dehydration you will likely throw it up to but not before your body has absorbed some of it also drinking for 2 days probably is not a good idea any more