Oh my, my daughter has had more UTIs than I can count I am afraid.
Most of the time, it is NOT due to a lack of hygiene. That is a great easy way to start figuring out the problem, but rarely works.
I would think that your ped will order some tests. There are a few things they will look at to make sure there is nothing structurally wrong with the systems down there. They will also make sure that there is not something going on like reflux...where the urine is pulled back in. These things can be corrected and nothing that you or your daughter are doing wrong.
In my daughters case, she was severely constipated. Which was news to me because she has a bowel movement every day. And if that goes on too long, their bodys don't know the feeling of when they have to go. So for us, it is going to the potty every two hours, backwards, making sure she voids everything, giving her fiber/mirilax, making sure she takes her vitamins and probiotics..and if everything is done perfectly every day, she doesn't get another one. However, that is not always the way it works unfortunately. She still gets them.
I have never ever had one in my life, so this is quite a learning experience for us. I hate taking her in with another one as I feel I have failed as a parent, which really, I have since I am not 100% on top of all those things above.
We have seen a urologist and a gastro to figure all of this out. It may take a while to figure it out. But UTIs, especially when they get to the point of a fever, are serious. Luckily, we know right when she gets one, her urine smells bad, she gets moody, and sometimes leaks. Only twice out of all the times has she ever had a fever. She has never ever had pain with it.
I am glad you are taking this seriously, but if your doctor doesn't think it is test worthy yet, I would start tracking bowel movements and have her go to the bathroom every two hours (not at night of course). Have her pee, then stand up, then sit down and try again..or have her sit backwards on the toilet (big pain with clothes on). This may help in the mean time.