I have a different answer for you.
I am a double board certified US doctor.
UTI means urinary tract infection.
It is impossible , without examination, to say where it starts, in the bladder, kidneys, etc.
If she is concerned, be evaluated now.
Do not assume anything.
If there are severe symptoms, or fever, it is more likely kidney.
It is not impossible for this to even start this way, happen in a day, 3 days , a week, all variations
Please click a positive rating on this post , at the top.
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I am board certified in integrative medicine, internal medicine, trained in functional medicine and homeopathy, etc. I am here daily: use my request link as needed and “for Dr. Thomas” in the question title. Give that link to friends, family, associates, etc. Find me as needed for correct, safe and accurate answers.