First UTI! HELP!

I was diagnosed with a UTI last week after my urine sample came back positive for bacteria and was prescribed Bactrim (2 pills a day, 3 days).

I finished the antibiotic course and felt nearly back to myself for two whole days afterwards, then I woke up this morning and all of my UTI symptoms have returned (urgency, pain, blood in urine)

I went to the immediate care center & did a urinalysis, and they detected no bacteria in my urine... they just gave me a prescription for Macrobid (3 times a day, for 10 days)

I’m so confused bacteria in my urine came negative, but my symptoms are horrendous. Has this ever happened to anyone?