The infection is still present and only the antibotics are doing is masking the root cause. The antibotics prescribed remove your good bacteria, hence, the bad over takes it and goes into other areas over time, similiar to the leaking gut example.
For immedate relief, try taking 1 teaspoon of Baking Soda with a glass of water and add some honey.
Or you can use Apple Cider Vinegar with a glass of water.
Either one, esp. baking soda you should see some changes.
Keep in mind this is removing the symptoms by placing back an "acidy" environment, and thats what you need to remove too much bad bacteria. The sugar in diets feeds the bad bacteria that overgrow and causes so many problems that it seems for a lot people do not show up in tests. Which we can agree now the tests are not all reliable when a person have physical symptoms, than something is wrong.
But no longer eat sugar in your diet, read the food labels that will list sugar in many different names. That sugar causes women so many problems due to our makeup down there. Also, quickly starting taking Multi Probiotic is the best for your stomache and urinary/uterus to help maintain your PH flora - make Plain Yogurt your best friend buddy. Drink more water, stop any surgary drinks, soft drinks and coffee. Feed your good bacteria. Eat some raw garlic to get to the root of the problem. Thats why you keep getting these UTI's because the initial cause never been dealt with just put to the side for awhile. Sorry you going thru this.
Take some multivitamin and mineral supplement, that helps to recharge your other inner workings.
I think it is the bad bacteria because it is in disguise not showing up on tests. We have to remember that some of these tests are only looking for particulars that reflect one thing or another and easily miss things, hence, your experience of passing out and passing blood (which is serious) and your initution Proves, something is wrong.
Dont soak yourself for awhile only showers. I read somewhere the Indians or mayble another cultural use to sit over herbs to clean our inner out. I need to get that recipe from a naturalist. At this point everything needs to be on the table to fix it. The woman, only wearing a wrapped towel waist down, sits on a chair ( that has small holes or ability to squat over it) that has the ability for a pot of the steamed herbs (think it was oregano leaves, thyme leaves, and two other ones, try to google more info on this ancient practice) but it natually and powerfully cleans the inner vag walls.
Don't give up. Keep looking for answers, but do change your diet as noted above.