Baby Boy - 3 month old not peeing for 4-5 hrs at night

Hey everyone, quick background: My boy is 3 month old and recently was diagnosed with bladder cystitis which caused UTI with fever. He usually pees adequate times i.e 10- 12 times. But tonight he did not pee for 4-5 hrs straight. He's not having any discomfort or pain or fussiness. May b I've become paranoid but is this ok?? Any ones boy having UTI pls share experiences.