Black/brown stringy things in 4 month old baby poop?

I was changing my daughters diaper and saw these black/brown stringy things. They almost look like legs of a bug? Or strings? She’s had blood in her poop before from a slight dairy allergy from breastfeeding but that looked nothing like this. She’s been exclusively breastfeeding up until last week when we got the ok from our pediatrician to start baby oatmeal cereal with iron so we’ve been doing that once a day, only a teaspoon or so mixed with breastmilk. Today is the first day she’s had these in her poop. She also didn’t have any oatmeal today.

Last night, over 24 hours ago, she did have a fever of 102 so I gave her Tylenol. It went down until this morning it was 100.9 so I gave her another dose of Tylenol and she’s been fever Free ever since. I called her dr and they said it could be teething and just keep an eye on her and bring her in if the fever gets worse but she didn’t have these when I called.

She’s also been acting fairly normal. Even with the fever yesterday. Just a little more tired but nothing too crazy. Still smiles at us etc.

so not sure if it’s all related?

You