Diarrhea in breastfed baby

Emily

What does diarrhea in a 2 month old BF baby look like? My son just had his first round of vaccines this past Thursday and now on saturday, has cold symptoms. My hubby told me his diaper had greenish looking stool as well. Normally his is yellow like mustard. I'm trying to find out if he has diarrhea but Google has wayyy too much diversity in it's information.