Could a sudden shift in diet and lifestyle "shock" my system and cause recurrent UTIs? Treatment advice?

Hi,
I would appreciate any advice anyone can offer. I have had somewhat recurrent UTIs since last September (two in the month of September 2009; one in December 2009; one in July 2010; one, at present, in September 2010). sexua| intercourse is obviously the impetus for these infections. We have both been tested for STIs.

I had eaten a high raw vegan diet (juiced vegetables daily; ate mostly salad, fruit, nuts, and small portions of cooked grains) before my boyfriend and I got together. Through no fault of his own, I found myself reverting back to a diet comprised mostly of processed sugars and starches. I had also recently moved, started a new graduate program, and ended an eight year long relationship last September. Basically, a lot of things changed in my life, and I found myself bombarded by stress. I am wondering if anyone else has suspected lifestyle and dietary changes to be possible causes of a urinary tract infection (perhaps along with other issues, such as candida).

I currently have an infection, and am trying to go the non- Antibiotic route. All of my urine cultures have shown that there is no pathogen in my urine (only Lactobacillus, which I do not think can cause an infection, but perhaps I am wrong). I took five rounds of Antibiotics this past year, and I am not doing it again!

Currently, I am taking D-Mannose, Apple Cider Vinegar in water, plenty of water, Calcium Citrate, probiotics, raw garlic, baking soda, and fresh vegetable juice. I am trying to eating small amounts of food and am trying to stick to alkalizing foods. I gave up cranberry juice; it caused me a lot of pain upon urination, and my urine was extremely concentrated.

Honestly, I am just at my wit's end. It has been one week since I noticed symptoms, and I don't know what to do or try. I don't even know what is wrong with me, which is perhaps the scariest part. As soon as I think I am getting better, one or two symptoms return. Urinating is painful; I often feel a constant need to urinate; etc. I also currently have a yeast infection, which led me to think perhaps the UTI is fungal.

Anyone have advice to offer? Deep down, I feel like I traded a pretty healthy lifestyle (which included daily yoga) in for an unhealthy, sedentary lifestyle. Perhaps the shift was too sudden. I have more anxiety and stress in my life and have gotten sick more this year than in previous years combined. I also exhibit many symptoms of adrenal fatigue, which I had experienced and been treated for in the past. Okay, I know I wrote a lot (I hope someone reads it)! Any help is greatly appreciated. Thank you!