Please help my five year old who is experiencing pain while voiding

Patient: I took my 5 yr old to see her pediatrician after she got out of school because she is experiencing severe pain while voiding. Her doctor took a urine sample and will get back to us tomorrow. I suspect it is a UTI. Can I give my 5yr old (55lbs) phenazopyridine hydrochloride to ease the pain? And if so, at what dosage? It’s sold otc.

Doctor: