Poop talk

So my daughter is 10 months has been extremely fussy for 3 days, fever off and on for 2 days, I’ve been getting it down with Tylenol and Motrin, she’s breastfed and is nursing every hour (or every 2 hours). She did vomit yesturday once but it may have been from too much milk ? Anyways, she pooped today and it was runny with black spots, this is not her normal poops. What is this ?

Is this a stomach bug or should I take her in ?

*she has no teeth so I thought was her teeth coming in but no teeth yet and it’s day 3