Baby has diarrhea???

My little man is 1 month old and for the whole month pretty much after birth he has had solid ish (playdough​) like yellow and black poop. But just yesterday he was sitting in my lap and let gas go a couple of times and I just thought oh ok he has gas but I went and checked his diaper and it was bright yellow and really soft.so I started looking on Google bc I haven't seen that before and it was freaking me out about how I need to call the doctors like now if he has diarrhea ... But it wasn't like super watery or anything so I'm not sure if it was.. this morning he had the same colored and textured diaper.... So I'm asking if anyone's babies when they got around 1 month or so their poop change texture ? He doesn't soil his diapers like I would think diarrhea in babies would (frequency wise) I am a major hipocondriac too and my husband thinks I'm just freaking out.