Toddler UTI & heart?

My 3 year old just started taking antibiotics yesterday for a UTI and we also gave her Motrin at night since she was screaming/crying that it hurts. This morning she was playing and then randomly said she feels her heart beating/pounding. She’s never said anything like that before? She has no fever or anything and seems completely fine besides being scared to pee

I just googled now how to check her heart rate and it’s at 104 which is completely normal so is this anything I should be worrying about & ask the doctor?

****The antibiotic is Cefdinir