research.

I have had yeast infections and UTIs before. Age 22.
I was clear for about 3 years and then one morning I woke up and I had the painful urination and contast need to urinate. This was due to intercourse. I can't tell the difference between yeast infection and UTIs, but I received anti biotics and it cleared up although I didnt finish the medication(forgot- I had a stupid moment). But since then, on the first days of my period I get slight discomfort while and after urinating. But only would happen for a short while on the first day of my period. The infection from before probably did not totally clear up, I'm guessing. This has been going on for about 4 months and now my pap test came back as abnormal. I have no symtpoms of HPV, although I know that most of the time you don't. And I use condoms and for the past 8 months have had the same partner. What is the likelihood that the test showed bacteria?
I'm going back to the gyno soon.

Is it dangerous to leave a vaginal yeast infection untreated? If it doesn't itch or if it doesn't smell, might it just go away naturally?

My friend has a yeast infection, but because she has diabetes her doctor says nothing can be done about it to get rid of it completely. She has experienced severe pain in her head for the past week, can this be due to her yeast infection?