Strong smelling urine? 5 month old

I’m a first time mom, but figured I’d post this in second time moms since you guys may know a bit more. My daughter is 5 months old and in the past 3 days, she’s had some strong smelling urine. If she pees just a little bit, it smells old pee, like she’s been in it for a while. But she is changed literally every time the line on her diaper goes blue immediately. She also hasn’t pooped in 3 days. I’m a bit concerned. I’m still waiting on a call back from her doc office to see if there are any appointments for this week. Anyone have experience in this? She’s also only formula fed. Thanks in advance.

Oh, she she’s also been acting completely normal, no fever, nothing. Sometimes fussy but only when she’s drooling like crazy and sticking teethers in her mouth from I’m assuming teething.